diff --git a/packages/api/src/client/config.ts b/packages/api/src/client/config.ts
index 38e74abda96..23fdc61759c 100644
--- a/packages/api/src/client/config.ts
+++ b/packages/api/src/client/config.ts
@@ -7,7 +7,7 @@ import {Api, ReqTypes, routesData, getReqSerializers, getReturnTypes} from "../r
  */
 export function getClient(config: IChainForkConfig, httpClient: IHttpClient): Api {
   const reqSerializers = getReqSerializers();
-  const returnTypes = getReturnTypes(config);
+  const returnTypes = getReturnTypes();
   // All routes return JSON, use a client auto-generator
   return generateGenericJsonClient<Api, ReqTypes>(routesData, reqSerializers, returnTypes, httpClient);
 }
diff --git a/packages/api/src/routes/config.ts b/packages/api/src/routes/config.ts
index 686b80007eb..6285073621f 100644
--- a/packages/api/src/routes/config.ts
+++ b/packages/api/src/routes/config.ts
@@ -1,9 +1,9 @@
-import {IBeaconPreset, BeaconPreset, activePreset} from "@chainsafe/lodestar-params";
-import {IChainConfig, ChainConfig} from "@chainsafe/lodestar-config";
+import {BeaconPreset} from "@chainsafe/lodestar-params";
+import {IChainConfig} from "@chainsafe/lodestar-config";
 import {Bytes32, Number64, phase0, ssz} from "@chainsafe/lodestar-types";
 import {mapValues} from "@chainsafe/lodestar-utils";
-import {ByteVectorType, ContainerType, Json, Type} from "@chainsafe/ssz";
-import {ArrayOf, ContainerData, ReqEmpty, reqEmpty, ReturnTypes, ReqSerializers, RoutesData, TypeJson} from "../utils";
+import {ByteVectorType, ContainerType} from "@chainsafe/ssz";
+import {ArrayOf, ContainerData, ReqEmpty, reqEmpty, ReturnTypes, ReqSerializers, RoutesData, sameType} from "../utils";
 
 // See /packages/api/src/routes/index.ts for reasoning and instructions to add new routes
 
@@ -12,16 +12,7 @@ export type DepositContract = {
   address: Bytes32;
 };
 
-export type ISpec = IBeaconPreset & IChainConfig;
-
-// eslint-disable-next-line @typescript-eslint/naming-convention
-export const Spec = new ContainerType<ISpec>({
-  fields: {
-    ...BeaconPreset.fields,
-    ...ChainConfig.fields,
-  },
-  expectedCase: "notransform",
-});
+export type Spec = BeaconPreset & IChainConfig;
 
 export type Api = {
   /**
@@ -37,15 +28,16 @@ export type Api = {
   getForkSchedule(): Promise<{data: phase0.Fork[]}>;
 
   /**
-   * Get spec params.
-   * Retrieve specification configuration used on this node.
-   * [Specification params list](https://github.com/ethereum/eth2.0-specs/blob/v1.0.0-rc.0/configs/mainnet/phase0.yaml)
+   * Retrieve specification configuration used on this node.  The configuration should include:
+   *  - Constants for all hard forks known by the beacon node, for example the [phase 0](https://github.com/ethereum/eth2.0-specs/blob/dev/specs/phase0/beacon-chain.md#constants) and [altair](https://github.com/ethereum/eth2.0-specs/blob/dev/specs/altair/beacon-chain.md#constants) values
+   *  - Presets for all hard forks supplied to the beacon node, for example the [phase 0](https://github.com/ethereum/eth2.0-specs/blob/dev/presets/mainnet/phase0.yaml) and [altair](https://github.com/ethereum/eth2.0-specs/blob/dev/presets/mainnet/altair.yaml) values
+   *  - Configuration for the beacon node, for example the [mainnet](https://github.com/ethereum/eth2.0-specs/blob/dev/configs/mainnet.yaml) values
    *
    * Values are returned with following format:
    * - any value starting with 0x in the spec is returned as a hex string
    * - numeric values are returned as a quoted integer
    */
-  getSpec(): Promise<{data: ISpec}>;
+  getSpec(): Promise<{data: Record<string, string>}>;
 };
 
 /**
@@ -63,15 +55,8 @@ export function getReqSerializers(): ReqSerializers<Api, ReqTypes> {
   return mapValues(routesData, () => reqEmpty);
 }
 
-function withJsonFilled<T>(dataType: Type<T>, fillWith: Json): TypeJson<{data: T}> {
-  return {
-    toJson: ({data}, opts) => ({data: dataType.toJson(data, opts)}),
-    fromJson: ({data}: {data: Json}, opts) => ({data: dataType.fromJson(Object.assign({}, fillWith, data), opts)}),
-  };
-}
-
 /* eslint-disable @typescript-eslint/naming-convention */
-export function getReturnTypes(config: IChainConfig): ReturnTypes<Api> {
+export function getReturnTypes(): ReturnTypes<Api> {
   const DepositContract = new ContainerType<DepositContract>({
     fields: {
       chainId: ssz.Number64,
@@ -87,6 +72,6 @@ export function getReturnTypes(config: IChainConfig): ReturnTypes<Api> {
   return {
     getDepositContract: ContainerData(DepositContract),
     getForkSchedule: ContainerData(ArrayOf(ssz.phase0.Fork)),
-    getSpec: withJsonFilled(Spec, Spec.toJson({...config, ...activePreset})),
+    getSpec: ContainerData(sameType()),
   };
 }
diff --git a/packages/api/src/utils/types.ts b/packages/api/src/utils/types.ts
index ccfe7aba146..0a54fca39c9 100644
--- a/packages/api/src/utils/types.ts
+++ b/packages/api/src/utils/types.ts
@@ -1,4 +1,4 @@
-import {ContainerType, IJsonOptions, Json, ListType, Type} from "@chainsafe/ssz";
+import {IJsonOptions, Json, ListType, Type} from "@chainsafe/ssz";
 import {ForkName} from "@chainsafe/lodestar-params";
 import {IChainForkConfig} from "@chainsafe/lodestar-config";
 import {objectToExpectedCase} from "@chainsafe/lodestar-utils";
@@ -111,8 +111,17 @@ export function ArrayOf<T>(elementType: Type<T>, limit = 1e6): ListType<T[]> {
  * data: T
  * ```
  */
-export function ContainerData<T>(dataType: Type<T>): ContainerType<{data: T}> {
-  return new ContainerType({fields: {data: dataType}, expectedCase: "notransform"});
+export function ContainerData<T>(dataType: TypeJson<T>): TypeJson<{data: T}> {
+  return {
+    toJson: ({data}, opts) => ({
+      data: dataType.toJson(data, opts),
+    }),
+    fromJson: ({data}: {data: Json}, opts) => {
+      return {
+        data: dataType.fromJson(data, opts),
+      };
+    },
+  };
 }
 
 /**
diff --git a/packages/api/test/unit/config.test.ts b/packages/api/test/unit/config.test.ts
index e8ec73eea0d..b77c8ffbdce 100644
--- a/packages/api/test/unit/config.test.ts
+++ b/packages/api/test/unit/config.test.ts
@@ -1,17 +1,19 @@
 import {ssz} from "@chainsafe/lodestar-types";
-import {config} from "@chainsafe/lodestar-config/default";
-import {Api, ReqTypes, Spec} from "../../src/routes/config";
+import {chainConfigToJson} from "@chainsafe/lodestar-config";
+import {config, chainConfig} from "@chainsafe/lodestar-config/default";
+import {activePreset, presetToJson} from "@chainsafe/lodestar-params";
+import {Api, ReqTypes, getReturnTypes} from "../../src/routes/config";
 import {getClient} from "../../src/client/config";
 import {getRoutes} from "../../src/server/config";
 import {runGenericServerTest} from "../utils/genericServerTest";
 import {expect} from "chai";
 
+/* eslint-disable @typescript-eslint/naming-convention */
+
 describe("config", () => {
-  it("Spec casing check", function () {
-    const defaultSpec = Spec.defaultValue();
-    const specJson = Spec.toJson(defaultSpec) as Record<string, string>;
-    expect(specJson["SLOTS_PER_EPOCH"] !== undefined).to.be.true;
-  });
+  const configJson = chainConfigToJson(chainConfig);
+  const presetJson = presetToJson(activePreset);
+  const jsonSpec = {...configJson, ...presetJson};
 
   runGenericServerTest<Api, ReqTypes>(config, getClient, getRoutes, {
     getDepositContract: {
@@ -29,7 +31,24 @@ describe("config", () => {
     },
     getSpec: {
       args: [],
-      res: {data: Spec.defaultValue()},
+      res: {data: jsonSpec},
     },
   });
+
+  it("Serialize Partial Spec object", () => {
+    const returnTypes = getReturnTypes();
+
+    const partialJsonSpec: Record<string, string> = {
+      PRESET_BASE: "mainnet",
+      DEPOSIT_CONTRACT_ADDRESS: "0xff50ed3d0ec03ac01d4c79aad74928bff48a7b2b",
+      GENESIS_FORK_VERSION: "0x00001020",
+      TERMINAL_TOTAL_DIFFICULTY: "115792089237316195423570985008687907853269984665640564039457584007913129639936",
+      MIN_GENESIS_TIME: "1606824000",
+    };
+
+    const jsonRes = returnTypes.getSpec.toJson({data: partialJsonSpec});
+    const specRes = returnTypes.getSpec.fromJson(jsonRes);
+
+    expect(specRes).to.deep.equal({data: partialJsonSpec}, "Wrong toJson -> fromJson");
+  });
 });
diff --git a/packages/cli/src/config/beaconParams.ts b/packages/cli/src/config/beaconParams.ts
index fcc9c5f523f..a1a96ebbd17 100644
--- a/packages/cli/src/config/beaconParams.ts
+++ b/packages/cli/src/config/beaconParams.ts
@@ -1,12 +1,11 @@
 import {
-  ChainConfig,
+  IChainConfig,
   createIChainForkConfig,
   createIChainConfig,
   IChainForkConfig,
-  IChainConfig,
-  parsePartialIChainConfigJson,
+  chainConfigFromJson,
 } from "@chainsafe/lodestar-config";
-import {writeFile, readFile} from "../util";
+import {readFile} from "../util";
 import {getNetworkBeaconParams, NetworkName} from "../networks";
 import {getGlobalPaths, IGlobalPaths} from "../paths/global";
 import {IBeaconParamsUnparsed} from "./types";
@@ -77,10 +76,10 @@ export function getBeaconParams({network, paramsFile, additionalParamsCli}: IBea
   });
 }
 
-export function writeBeaconParams(filepath: string, params: IChainConfig): void {
-  writeFile(filepath, ChainConfig.toJson(params));
-}
-
 function readBeaconParams(filepath: string): IBeaconParamsUnparsed {
   return readFile(filepath) ?? {};
 }
+
+export function parsePartialIChainConfigJson(input: Record<string, unknown>): Partial<IChainConfig> {
+  return chainConfigFromJson(input);
+}
diff --git a/packages/cli/src/options/paramsOptions.ts b/packages/cli/src/options/paramsOptions.ts
index 229f92bded3..fdd41239390 100644
--- a/packages/cli/src/options/paramsOptions.ts
+++ b/packages/cli/src/options/paramsOptions.ts
@@ -1,7 +1,7 @@
 import {Options} from "yargs";
+import {IChainConfig, chainConfigTypes} from "@chainsafe/lodestar-config";
 import {IBeaconParamsUnparsed} from "../config/types";
 import {ObjectKeys, ICliCommandOptions} from "../util";
-import {ChainConfig, IChainConfig} from "@chainsafe/lodestar-config";
 
 // No options are statically declared
 // If an arbitraty key notation is used, it removes typesafety on most of this CLI arg parsing code.
@@ -17,17 +17,14 @@ export type IParamsArgs = Record<never, never> & ITerminalPowArgs;
 const getArgKey = (key: keyof IBeaconParamsUnparsed): string => `params.${key}`;
 
 export function parseBeaconParamsArgs(args: Record<string, string | number>): IBeaconParamsUnparsed {
-  return ((ObjectKeys(ChainConfig.fields) as unknown) as (keyof IChainConfig)[]).reduce(
-    (beaconParams: Partial<IBeaconParamsUnparsed>, key) => {
-      const value = args[getArgKey(key)];
-      if (value != null) beaconParams[key] = value;
-      return beaconParams;
-    },
-    {}
-  );
+  return ObjectKeys(chainConfigTypes).reduce((beaconParams: Partial<IBeaconParamsUnparsed>, key) => {
+    const value = args[getArgKey(key)];
+    if (value != null) beaconParams[key] = value;
+    return beaconParams;
+  }, {});
 }
 
-const paramsOptionsByName = ((ObjectKeys(ChainConfig.fields) as unknown) as (keyof IChainConfig)[]).reduce(
+const paramsOptionsByName = ObjectKeys(chainConfigTypes).reduce(
   (options: Record<string, Options>, key): Record<string, Options> => ({
     ...options,
     [getArgKey(key)]: {
diff --git a/packages/config/README.md b/packages/config/README.md
index 9ece40c4f61..0265e1ab083 100644
--- a/packages/config/README.md
+++ b/packages/config/README.md
@@ -8,7 +8,6 @@
 
 > This package is part of [ChainSafe's Lodestar](https://lodestar.chainsafe.io) project
 
-
 Lodestar defines all [network configuration variables](https://github.com/ethereum/eth2.0-specs/tree/dev/configs) defined in the [Ethereum Consensus / Eth2 spec](https://github.com/ethereum/eth2.0-specs). This tooling may be used to configure testnets, ingest mainnet/testnet config variables, or be used in downstream Lodestar libraries.
 
 ## Installation
@@ -50,7 +49,7 @@ chainConfig.SECONDS_PER_SLOT === 12;
 There are also utility functions to help create a `IChainConfig` from unknown input and partial configs.
 
 ```typescript
-import {createIChainConfig, IChainConfig, parsePartialIChainConfigJson} from "@chainsafe/lodestar-config";
+import {createIChainConfig, IChainConfig, chainConfigFromJson} from "@chainsafe/lodestar-config";
 
 // example config
 let chainConfigObj: Record<string, unknown> = {
@@ -76,9 +75,9 @@ let chainConfigObj: Record<string, unknown> = {
   INACTIVITY_SCORE_RECOVERY_RATE: 16,
   ALTAIR_FORK_VERSION: "0x01004811",
   ALTAIR_FORK_EPOCH: 10,
-}
+};
 
-const partialChainConfig: Partial<IChainConfig> = parsePartialIChainConfigJson(chainConfigObj);
+const partialChainConfig: Partial<IChainConfig> = chainConfigFromJson(chainConfigObj);
 
 // Fill in the missing values with mainnet default values
 const chainConfig: IChainConfig = createIChainConfig(partialChainConfig);
@@ -88,7 +87,7 @@ const chainConfig: IChainConfig = createIChainConfig(partialChainConfig);
 
 The variables described in the spec can be used to assemble a more structured 'fork schedule'. This info is organized as `IForkConfig` in the Lodestar config package. In practice, the `IChainConfig` and `IForkConfig` are usually combined as a `IChainForkConfig`.
 
-A `IForkConfig` provides methods to select the fork info, fork name, fork version, or fork ssz types given a slot. 
+A `IForkConfig` provides methods to select the fork info, fork name, fork version, or fork ssz types given a slot.
 
 ```typescript
 import {GENESIS_SLOT} from "@chainsafe/lodestar-params";
diff --git a/packages/config/src/chainConfig/index.ts b/packages/config/src/chainConfig/index.ts
index cfb5b697bd2..747412957e4 100644
--- a/packages/config/src/chainConfig/index.ts
+++ b/packages/config/src/chainConfig/index.ts
@@ -1,11 +1,9 @@
-import {Json} from "@chainsafe/ssz";
 import {ACTIVE_PRESET} from "@chainsafe/lodestar-params";
 import {IChainConfig} from "./types";
-import {ChainConfig} from "./sszTypes";
 import {defaultChainConfig} from "./default";
 
+export {chainConfigToJson, chainConfigFromJson} from "./json";
 export * from "./types";
-export * from "./sszTypes";
 export * from "./default";
 
 /**
@@ -27,20 +25,3 @@ export function createIChainConfig(input: Partial<IChainConfig>): IChainConfig {
   }
   return config;
 }
-
-export function parsePartialIChainConfigJson(input?: Record<string, unknown>): Partial<IChainConfig> {
-  if (!input) {
-    return {};
-  }
-
-  const config = {};
-
-  // Parse config input values, if they exist
-  for (const [fieldName, fieldType] of Object.entries(ChainConfig.fields)) {
-    if (input[fieldName] != null) {
-      (config as Record<string, unknown>)[fieldName] = fieldType.fromJson(input[fieldName] as Json);
-    }
-  }
-
-  return config;
-}
diff --git a/packages/config/src/chainConfig/json.ts b/packages/config/src/chainConfig/json.ts
new file mode 100644
index 00000000000..751e087d9b8
--- /dev/null
+++ b/packages/config/src/chainConfig/json.ts
@@ -0,0 +1,78 @@
+import {fromHexString, toHexString} from "@chainsafe/ssz";
+import {IChainConfig, chainConfigTypes, SpecValue, SpecValueTypeName} from "./types";
+
+const MAX_UINT64_JSON = "18446744073709551615";
+
+export function chainConfigToJson(config: IChainConfig): Record<string, string> {
+  const json: Record<string, string> = {};
+
+  for (const key of Object.keys(config) as (keyof IChainConfig)[]) {
+    json[key] = serializeSpecValue(config[key], chainConfigTypes[key]);
+  }
+
+  return json;
+}
+
+export function chainConfigFromJson(json: Record<string, unknown>): IChainConfig {
+  const config = {} as IChainConfig;
+
+  for (const key of Object.keys(json) as (keyof IChainConfig)[]) {
+    config[key] = deserializeSpecValue(json[key], chainConfigTypes[key]) as never;
+  }
+
+  return config;
+}
+
+export function serializeSpecValue(value: SpecValue, typeName: SpecValueTypeName): string {
+  switch (typeName) {
+    case "number":
+      if (typeof value !== "number") {
+        throw Error(`Invalid value ${value} expected number`);
+      }
+      if (value === Infinity) {
+        return MAX_UINT64_JSON;
+      }
+      return value.toString(10);
+
+    case "bigint":
+      if (typeof value !== "bigint") {
+        throw Error(`Invalid value ${value} expected bigint`);
+      }
+      return value.toString(10);
+
+    case "bytes":
+      if (!(value instanceof Uint8Array)) {
+        throw Error(`Invalid value ${value} expected Uint8Array`);
+      }
+      return toHexString(value);
+
+    case "string":
+      if (typeof value !== "string") {
+        throw Error(`Invalid value ${value} expected string`);
+      }
+      return value;
+  }
+}
+
+export function deserializeSpecValue(valueStr: unknown, typeName: SpecValueTypeName): SpecValue {
+  if (typeof valueStr !== "string") {
+    throw Error(`Invalid value ${valueStr} expected string`);
+  }
+
+  switch (typeName) {
+    case "number":
+      if (valueStr === MAX_UINT64_JSON) {
+        return Infinity;
+      }
+      return parseInt(valueStr, 10);
+
+    case "bigint":
+      return BigInt(valueStr);
+
+    case "bytes":
+      return fromHexString(valueStr);
+
+    case "string":
+      return valueStr;
+  }
+}
diff --git a/packages/config/src/chainConfig/networks/mainnet.ts b/packages/config/src/chainConfig/networks/mainnet.ts
index b382c986613..ebdd6a174dd 100644
--- a/packages/config/src/chainConfig/networks/mainnet.ts
+++ b/packages/config/src/chainConfig/networks/mainnet.ts
@@ -1,6 +1,6 @@
 /* eslint-disable @typescript-eslint/naming-convention */
 import {fromHexString as b} from "@chainsafe/ssz";
-import {IChainConfig} from "..";
+import {IChainConfig} from "../types";
 import {chainConfig as mainnet} from "../presets/mainnet";
 
 /* eslint-disable max-len */
diff --git a/packages/config/src/chainConfig/networks/prater.ts b/packages/config/src/chainConfig/networks/prater.ts
index 4c4f8e472a2..085d1c9231b 100644
--- a/packages/config/src/chainConfig/networks/prater.ts
+++ b/packages/config/src/chainConfig/networks/prater.ts
@@ -1,6 +1,6 @@
 /* eslint-disable @typescript-eslint/naming-convention */
 import {fromHexString as b} from "@chainsafe/ssz";
-import {IChainConfig} from "..";
+import {IChainConfig} from "../types";
 import {chainConfig as mainnet} from "../presets/mainnet";
 
 /* eslint-disable max-len */
diff --git a/packages/config/src/chainConfig/networks/pyrmont.ts b/packages/config/src/chainConfig/networks/pyrmont.ts
index 1c2889e0837..168290622b4 100644
--- a/packages/config/src/chainConfig/networks/pyrmont.ts
+++ b/packages/config/src/chainConfig/networks/pyrmont.ts
@@ -1,6 +1,6 @@
 /* eslint-disable @typescript-eslint/naming-convention */
 import {fromHexString as b} from "@chainsafe/ssz";
-import {IChainConfig} from "..";
+import {IChainConfig} from "../types";
 import {chainConfig as mainnet} from "../presets/mainnet";
 
 /* eslint-disable max-len */
diff --git a/packages/config/src/chainConfig/types.ts b/packages/config/src/chainConfig/types.ts
index a7dfc16bfd3..b5a03aa5981 100644
--- a/packages/config/src/chainConfig/types.ts
+++ b/packages/config/src/chainConfig/types.ts
@@ -1,10 +1,11 @@
-/* eslint-disable @typescript-eslint/naming-convention */
 import {PresetName} from "@chainsafe/lodestar-params";
 
+/* eslint-disable @typescript-eslint/naming-convention */
+
 /**
  * Run-time chain configuration
  */
-export interface IChainConfig {
+export type IChainConfig = {
   PRESET_BASE: PresetName;
 
   // Transition
@@ -42,10 +43,81 @@ export interface IChainConfig {
   EJECTION_BALANCE: number;
   MIN_PER_EPOCH_CHURN_LIMIT: number;
   CHURN_LIMIT_QUOTIENT: number;
+
+  // Proposer boost
   PROPOSER_SCORE_BOOST: number;
 
   // Deposit contract
   DEPOSIT_CHAIN_ID: number;
   DEPOSIT_NETWORK_ID: number;
   DEPOSIT_CONTRACT_ADDRESS: Uint8Array;
-}
+};
+
+export const chainConfigTypes: SpecTypes<IChainConfig> = {
+  PRESET_BASE: "string",
+
+  // Transition
+  TERMINAL_TOTAL_DIFFICULTY: "bigint",
+  TERMINAL_BLOCK_HASH: "bytes",
+  TERMINAL_BLOCK_HASH_ACTIVATION_EPOCH: "number",
+
+  // Genesis
+  MIN_GENESIS_ACTIVE_VALIDATOR_COUNT: "number",
+  MIN_GENESIS_TIME: "number",
+  GENESIS_FORK_VERSION: "bytes",
+  GENESIS_DELAY: "number",
+
+  // Forking
+  // Altair
+  ALTAIR_FORK_VERSION: "bytes",
+  ALTAIR_FORK_EPOCH: "number",
+  // Bellatrix
+  BELLATRIX_FORK_VERSION: "bytes",
+  BELLATRIX_FORK_EPOCH: "number",
+  // Sharding
+  SHARDING_FORK_VERSION: "bytes",
+  SHARDING_FORK_EPOCH: "number",
+
+  // Time parameters
+  SECONDS_PER_SLOT: "number",
+  SECONDS_PER_ETH1_BLOCK: "number",
+  MIN_VALIDATOR_WITHDRAWABILITY_DELAY: "number",
+  SHARD_COMMITTEE_PERIOD: "number",
+  ETH1_FOLLOW_DISTANCE: "number",
+
+  // Validator cycle
+  INACTIVITY_SCORE_BIAS: "number",
+  INACTIVITY_SCORE_RECOVERY_RATE: "number",
+  EJECTION_BALANCE: "number",
+  MIN_PER_EPOCH_CHURN_LIMIT: "number",
+  CHURN_LIMIT_QUOTIENT: "number",
+
+  // Proposer boost
+  PROPOSER_SCORE_BOOST: "number",
+
+  // Deposit contract
+  DEPOSIT_CHAIN_ID: "number",
+  DEPOSIT_NETWORK_ID: "number",
+  DEPOSIT_CONTRACT_ADDRESS: "bytes",
+};
+
+/** Allows values in a Spec file */
+export type SpecValue = number | bigint | Uint8Array | string;
+
+/** Type value name of each spec field. Numbers are ignored since they are the most common */
+export type SpecValueType<V extends SpecValue> = V extends number
+  ? "number"
+  : V extends bigint
+  ? "bigint"
+  : V extends Uint8Array
+  ? "bytes"
+  : V extends string
+  ? "string"
+  : never;
+
+/** All possible type names for a SpecValue */
+export type SpecValueTypeName = SpecValueType<SpecValue>;
+
+export type SpecTypes<Spec extends Record<string, SpecValue>> = {
+  [K in keyof Spec]: SpecValueType<Spec[K]>;
+};
diff --git a/packages/config/test/unit/json.test.ts b/packages/config/test/unit/json.test.ts
new file mode 100644
index 00000000000..9b614baebb9
--- /dev/null
+++ b/packages/config/test/unit/json.test.ts
@@ -0,0 +1,12 @@
+import {expect} from "chai";
+import {chainConfigFromJson, chainConfigToJson} from "../../src";
+import {chainConfig} from "../../src/default";
+
+describe("chainConfig JSON", () => {
+  it("Convert to and from JSON", () => {
+    const json = chainConfigToJson(chainConfig);
+    const chainConfigRes = chainConfigFromJson(json);
+
+    expect(chainConfigRes).to.deep.equal(chainConfig);
+  });
+});
diff --git a/packages/lodestar/src/api/impl/config/index.ts b/packages/lodestar/src/api/impl/config/index.ts
index ed8d5ea69a2..645eed237c8 100644
--- a/packages/lodestar/src/api/impl/config/index.ts
+++ b/packages/lodestar/src/api/impl/config/index.ts
@@ -1,17 +1,27 @@
 import {routes} from "@chainsafe/lodestar-api";
-import {ChainConfig} from "@chainsafe/lodestar-config";
-import * as params from "@chainsafe/lodestar-params";
+import {chainConfigToJson} from "@chainsafe/lodestar-config";
+import {activePreset, presetToJson} from "@chainsafe/lodestar-params";
 import {ApiModules} from "../types";
 
 export function getConfigApi({config}: Pick<ApiModules, "config">): routes.config.Api {
-  const specWithExtraKeys = {...params, ...config};
-  const spec = {} as routes.config.ISpec;
-  ([
-    ...Object.keys(ChainConfig.fields),
-    ...Object.keys(params.BeaconPreset.fields),
-  ] as (keyof routes.config.ISpec)[]).forEach((fieldName) => {
-    ((spec as unknown) as Record<string, unknown>)[fieldName] = specWithExtraKeys[fieldName];
-  });
+  // Retrieve specification configuration used on this node.  The configuration should include:
+  //  - Constants for all hard forks known by the beacon node, for example the
+  //    [phase 0](https://github.com/ethereum/eth2.0-specs/blob/dev/specs/phase0/beacon-chain.md#constants) and
+  //    [altair](https://github.com/ethereum/eth2.0-specs/blob/dev/specs/altair/beacon-chain.md#constants) values
+  //  - Presets for all hard forks supplied to the beacon node, for example the
+  //    [phase 0](https://github.com/ethereum/eth2.0-specs/blob/dev/presets/mainnet/phase0.yaml) and
+  //    [altair](https://github.com/ethereum/eth2.0-specs/blob/dev/presets/mainnet/altair.yaml) values
+  //  - Configuration for the beacon node, for example the [mainnet](https://github.com/ethereum/eth2.0-specs/blob/dev/configs/mainnet.yaml) values
+
+  let jsonSpec: Record<string, string> | null = null;
+  function getJsonSpec(): Record<string, string> {
+    // TODO: Include static constants exported in @chainsafe/lodestar-params (i.e. DOMAIN_BEACON_PROPOSER)
+    const configJson = chainConfigToJson(config);
+    const presetJson = presetToJson(activePreset);
+    jsonSpec = {...configJson, ...presetJson};
+    return jsonSpec;
+  }
+
   return {
     async getForkSchedule() {
       const forkInfos = Object.values(config.forks);
@@ -34,7 +44,7 @@ export function getConfigApi({config}: Pick<ApiModules, "config">): routes.confi
 
     async getSpec() {
       return {
-        data: spec,
+        data: getJsonSpec(),
       };
     },
   };
diff --git a/packages/lodestar/test/unit/api/impl/config/config.test.ts b/packages/lodestar/test/unit/api/impl/config/config.test.ts
index aabb8583c3b..991ddd70e04 100644
--- a/packages/lodestar/test/unit/api/impl/config/config.test.ts
+++ b/packages/lodestar/test/unit/api/impl/config/config.test.ts
@@ -1,9 +1,6 @@
-// eslint-disable-next-line no-restricted-imports
-import {IChainConfig} from "@chainsafe/lodestar-config";
 import {config} from "@chainsafe/lodestar-config/default";
 import {expect} from "chai";
 import {getConfigApi} from "../../../../../src/api/impl/config";
-import {toJson} from "@chainsafe/lodestar-utils";
 
 describe("config api implementation", function () {
   let api: ReturnType<typeof getConfigApi>;
@@ -29,11 +26,10 @@ describe("config api implementation", function () {
 
   describe("getSpec", function () {
     it("should get the spec", async function () {
-      const {data: spec} = await api.getSpec();
-      const specJson = (spec as unknown) as IChainConfig;
+      const {data: specJson} = await api.getSpec();
 
-      expect(toJson(specJson.SECONDS_PER_ETH1_BLOCK)).to.equal(14, "Wrong SECONDS_PER_ETH1_BLOCK");
-      expect(toJson(specJson.DEPOSIT_CONTRACT_ADDRESS)).to.equal(
+      expect(specJson.SECONDS_PER_ETH1_BLOCK).to.equal("14", "Wrong SECONDS_PER_ETH1_BLOCK");
+      expect(specJson.DEPOSIT_CONTRACT_ADDRESS).to.equal(
         "0x1234567890123456789012345678901234567890",
         "Wrong DEPOSIT_CONTRACT_ADDRESS"
       );
diff --git a/packages/params/package.json b/packages/params/package.json
index a8feeb9158c..60fb0f80757 100644
--- a/packages/params/package.json
+++ b/packages/params/package.json
@@ -42,9 +42,7 @@
     "beacon",
     "blockchain"
   ],
-  "dependencies": {
-    "@chainsafe/ssz": "^0.8.20"
-  },
+  "dependencies": {},
   "devDependencies": {
     "@types/js-yaml": "^4.0.3",
     "axios": "^0.21.0",
diff --git a/packages/params/src/index.ts b/packages/params/src/index.ts
index 3348aecb6f8..faf11b59251 100644
--- a/packages/params/src/index.ts
+++ b/packages/params/src/index.ts
@@ -1,11 +1,13 @@
-import {PresetName} from "./preset";
+import {PresetName} from "./presetName";
 import {preset as mainnet} from "./presets/mainnet";
 import {preset as minimal} from "./presets/minimal";
 import {presetStatus} from "./presetStatus";
 import {userSelectedPreset} from "./setPreset";
 
-export * from "./preset";
+export * from "./interface";
 export {ForkName} from "./forkName";
+export {presetToJson} from "./json";
+export {PresetName};
 
 const presets = {
   [PresetName.mainnet]: mainnet,
@@ -23,7 +25,7 @@ presetStatus.frozen = true;
  *
  * The active preset can be manually overridden with `setActivePreset`
  */
-export const ACTIVE_PRESET: PresetName =
+export const ACTIVE_PRESET =
   userSelectedPreset || PresetName[process?.env?.LODESTAR_PRESET as PresetName] || PresetName.mainnet;
 export const activePreset = presets[ACTIVE_PRESET];
 
diff --git a/packages/params/src/preset/altair/interface.ts b/packages/params/src/interface/altair.ts
similarity index 90%
rename from packages/params/src/preset/altair/interface.ts
rename to packages/params/src/interface/altair.ts
index a2b6c89a917..e0b28756001 100644
--- a/packages/params/src/preset/altair/interface.ts
+++ b/packages/params/src/interface/altair.ts
@@ -1,6 +1,5 @@
 /* eslint-disable @typescript-eslint/naming-convention */
-
-export interface IAltairPreset {
+export type AltairPreset = {
   SYNC_COMMITTEE_SIZE: number;
   EPOCHS_PER_SYNC_COMMITTEE_PERIOD: number;
   INACTIVITY_PENALTY_QUOTIENT_ALTAIR: number;
@@ -8,4 +7,4 @@ export interface IAltairPreset {
   PROPORTIONAL_SLASHING_MULTIPLIER_ALTAIR: number;
   MIN_SYNC_COMMITTEE_PARTICIPANTS: number;
   UPDATE_TIMEOUT: number;
-}
+};
diff --git a/packages/params/src/preset/bellatrix/interface.ts b/packages/params/src/interface/bellatrix.ts
similarity index 90%
rename from packages/params/src/preset/bellatrix/interface.ts
rename to packages/params/src/interface/bellatrix.ts
index d40d639737e..e250e4cbda2 100644
--- a/packages/params/src/preset/bellatrix/interface.ts
+++ b/packages/params/src/interface/bellatrix.ts
@@ -1,6 +1,5 @@
 /* eslint-disable @typescript-eslint/naming-convention */
-
-export interface IBellatrixPreset {
+export type BellatrixPreset = {
   INACTIVITY_PENALTY_QUOTIENT_BELLATRIX: number;
   MIN_SLASHING_PENALTY_QUOTIENT_BELLATRIX: number;
   PROPORTIONAL_SLASHING_MULTIPLIER_BELLATRIX: number;
@@ -8,4 +7,4 @@ export interface IBellatrixPreset {
   MAX_TRANSACTIONS_PER_PAYLOAD: number;
   BYTES_PER_LOGS_BLOOM: number;
   MAX_EXTRA_DATA_BYTES: number;
-}
+};
diff --git a/packages/params/src/interface/index.ts b/packages/params/src/interface/index.ts
new file mode 100644
index 00000000000..8b344c57a41
--- /dev/null
+++ b/packages/params/src/interface/index.ts
@@ -0,0 +1,5 @@
+import {Phase0Preset} from "./phase0";
+import {AltairPreset} from "./altair";
+import {BellatrixPreset} from "./bellatrix";
+
+export type BeaconPreset = Phase0Preset & AltairPreset & BellatrixPreset;
diff --git a/packages/params/src/preset/phase0/interface.ts b/packages/params/src/interface/phase0.ts
similarity index 95%
rename from packages/params/src/preset/phase0/interface.ts
rename to packages/params/src/interface/phase0.ts
index 16935f9ff4f..bbf4189bfdf 100644
--- a/packages/params/src/preset/phase0/interface.ts
+++ b/packages/params/src/interface/phase0.ts
@@ -1,6 +1,5 @@
 /* eslint-disable @typescript-eslint/naming-convention */
-
-export interface IPhase0Preset {
+export type Phase0Preset = {
   // Misc
   MAX_COMMITTEES_PER_SLOT: number;
   TARGET_COMMITTEE_SIZE: number;
@@ -16,7 +15,7 @@ export interface IPhase0Preset {
   SAFE_SLOTS_TO_UPDATE_JUSTIFIED: number;
 
   // Gwei Values
-  MIN_DEPOSIT_AMOUNT: bigint;
+  MIN_DEPOSIT_AMOUNT: number;
   MAX_EFFECTIVE_BALANCE: number;
   EFFECTIVE_BALANCE_INCREMENT: number;
 
@@ -49,4 +48,4 @@ export interface IPhase0Preset {
   MAX_ATTESTATIONS: number;
   MAX_DEPOSITS: number;
   MAX_VOLUNTARY_EXITS: number;
-}
+};
diff --git a/packages/params/src/json.ts b/packages/params/src/json.ts
new file mode 100644
index 00000000000..99abc3730bd
--- /dev/null
+++ b/packages/params/src/json.ts
@@ -0,0 +1,23 @@
+import {BeaconPreset} from "./interface";
+
+/**
+ * Render BeaconPreset to JSON strings
+ * - Numbers: Render as a quoted decimal string
+ */
+export function presetToJson(preset: BeaconPreset): Record<string, string> {
+  const json: Record<string, string> = {};
+
+  for (const key of Object.keys(preset) as (keyof BeaconPreset)[]) {
+    json[key] = serializePresetValue(preset[key]);
+  }
+
+  return json;
+}
+
+/**
+ * Type Wrapper to ensure that all values of BeaconPreset are number.
+ * If there are more types, expand this function with a type switch
+ */
+function serializePresetValue(value: number): string {
+  return value.toString(10);
+}
diff --git a/packages/params/src/preset/altair/index.ts b/packages/params/src/preset/altair/index.ts
deleted file mode 100644
index 20616ee7a7f..00000000000
--- a/packages/params/src/preset/altair/index.ts
+++ /dev/null
@@ -1,2 +0,0 @@
-export * from "./interface";
-export * from "./ssz";
diff --git a/packages/params/src/preset/altair/ssz.ts b/packages/params/src/preset/altair/ssz.ts
deleted file mode 100644
index ce0e303cda7..00000000000
--- a/packages/params/src/preset/altair/ssz.ts
+++ /dev/null
@@ -1,21 +0,0 @@
-/* eslint-disable @typescript-eslint/naming-convention */
-
-import {ContainerType, NumberUintType} from "@chainsafe/ssz";
-
-import {IAltairPreset} from "./interface";
-
-const Number64 = new NumberUintType({byteLength: 8});
-
-export const AltairPreset = new ContainerType<IAltairPreset>({
-  fields: {
-    SYNC_COMMITTEE_SIZE: Number64,
-    EPOCHS_PER_SYNC_COMMITTEE_PERIOD: Number64,
-    INACTIVITY_PENALTY_QUOTIENT_ALTAIR: Number64,
-    MIN_SLASHING_PENALTY_QUOTIENT_ALTAIR: Number64,
-    PROPORTIONAL_SLASHING_MULTIPLIER_ALTAIR: Number64,
-    MIN_SYNC_COMMITTEE_PARTICIPANTS: Number64,
-    UPDATE_TIMEOUT: Number64,
-  },
-  // Expected and container fields are the same here
-  expectedCase: "notransform",
-});
diff --git a/packages/params/src/preset/bellatrix/index.ts b/packages/params/src/preset/bellatrix/index.ts
deleted file mode 100644
index 20616ee7a7f..00000000000
--- a/packages/params/src/preset/bellatrix/index.ts
+++ /dev/null
@@ -1,2 +0,0 @@
-export * from "./interface";
-export * from "./ssz";
diff --git a/packages/params/src/preset/bellatrix/ssz.ts b/packages/params/src/preset/bellatrix/ssz.ts
deleted file mode 100644
index 5080e8cbf9d..00000000000
--- a/packages/params/src/preset/bellatrix/ssz.ts
+++ /dev/null
@@ -1,21 +0,0 @@
-/* eslint-disable @typescript-eslint/naming-convention */
-
-import {ContainerType, NumberUintType} from "@chainsafe/ssz";
-
-import {IBellatrixPreset} from "./interface";
-
-const Number64 = new NumberUintType({byteLength: 8});
-
-export const BellatrixPreset = new ContainerType<IBellatrixPreset>({
-  fields: {
-    INACTIVITY_PENALTY_QUOTIENT_BELLATRIX: Number64,
-    MIN_SLASHING_PENALTY_QUOTIENT_BELLATRIX: Number64,
-    PROPORTIONAL_SLASHING_MULTIPLIER_BELLATRIX: Number64,
-    MAX_BYTES_PER_TRANSACTION: Number64,
-    MAX_TRANSACTIONS_PER_PAYLOAD: Number64,
-    BYTES_PER_LOGS_BLOOM: Number64,
-    MAX_EXTRA_DATA_BYTES: Number64,
-  },
-  // Expected and container fields are the same here
-  expectedCase: "notransform",
-});
diff --git a/packages/params/src/preset/index.ts b/packages/params/src/preset/index.ts
deleted file mode 100644
index 803a60a277e..00000000000
--- a/packages/params/src/preset/index.ts
+++ /dev/null
@@ -1,7 +0,0 @@
-export * from "./presetName";
-export * from "./interface";
-export * from "./ssz";
-
-export * from "./phase0";
-export * from "./altair";
-export * from "./bellatrix";
diff --git a/packages/params/src/preset/interface.ts b/packages/params/src/preset/interface.ts
deleted file mode 100644
index ece659102d0..00000000000
--- a/packages/params/src/preset/interface.ts
+++ /dev/null
@@ -1,10 +0,0 @@
-/* eslint-disable @typescript-eslint/naming-convention */
-/**
- * @module params
- */
-
-import {IPhase0Preset} from "./phase0";
-import {IAltairPreset} from "./altair";
-import {IBellatrixPreset} from "./bellatrix";
-
-export type IBeaconPreset = IPhase0Preset & IAltairPreset & IBellatrixPreset;
diff --git a/packages/params/src/preset/phase0/index.ts b/packages/params/src/preset/phase0/index.ts
deleted file mode 100644
index 20616ee7a7f..00000000000
--- a/packages/params/src/preset/phase0/index.ts
+++ /dev/null
@@ -1,2 +0,0 @@
-export * from "./interface";
-export * from "./ssz";
diff --git a/packages/params/src/preset/phase0/ssz.ts b/packages/params/src/preset/phase0/ssz.ts
deleted file mode 100644
index 40f54595664..00000000000
--- a/packages/params/src/preset/phase0/ssz.ts
+++ /dev/null
@@ -1,60 +0,0 @@
-/* eslint-disable @typescript-eslint/naming-convention */
-
-import {IPhase0Preset} from "./interface";
-import {ContainerType, BigIntUintType, NumberUintType} from "@chainsafe/ssz";
-
-const Number64 = new NumberUintType({byteLength: 8});
-const BigInt64 = new BigIntUintType({byteLength: 8});
-
-export const Phase0Preset = new ContainerType<IPhase0Preset>({
-  fields: {
-    // Misc
-    MAX_COMMITTEES_PER_SLOT: Number64,
-    TARGET_COMMITTEE_SIZE: Number64,
-    MAX_VALIDATORS_PER_COMMITTEE: Number64,
-    SHUFFLE_ROUND_COUNT: Number64,
-    HYSTERESIS_QUOTIENT: Number64,
-    HYSTERESIS_DOWNWARD_MULTIPLIER: Number64,
-    HYSTERESIS_UPWARD_MULTIPLIER: Number64,
-
-    // Fork choice
-    SAFE_SLOTS_TO_UPDATE_JUSTIFIED: Number64,
-
-    // Gwei Values
-    MIN_DEPOSIT_AMOUNT: BigInt64,
-    MAX_EFFECTIVE_BALANCE: Number64,
-    EFFECTIVE_BALANCE_INCREMENT: Number64,
-
-    // Time parameters
-    MIN_ATTESTATION_INCLUSION_DELAY: Number64,
-    SLOTS_PER_EPOCH: Number64,
-    MIN_SEED_LOOKAHEAD: Number64,
-    MAX_SEED_LOOKAHEAD: Number64,
-    EPOCHS_PER_ETH1_VOTING_PERIOD: Number64,
-    SLOTS_PER_HISTORICAL_ROOT: Number64,
-    MIN_EPOCHS_TO_INACTIVITY_PENALTY: Number64,
-
-    // State vector lengths
-    EPOCHS_PER_HISTORICAL_VECTOR: Number64,
-    EPOCHS_PER_SLASHINGS_VECTOR: Number64,
-    HISTORICAL_ROOTS_LIMIT: Number64,
-    VALIDATOR_REGISTRY_LIMIT: Number64,
-
-    // Reward and penalty quotients
-    BASE_REWARD_FACTOR: Number64,
-    WHISTLEBLOWER_REWARD_QUOTIENT: Number64,
-    PROPOSER_REWARD_QUOTIENT: Number64,
-    INACTIVITY_PENALTY_QUOTIENT: Number64,
-    MIN_SLASHING_PENALTY_QUOTIENT: Number64,
-    PROPORTIONAL_SLASHING_MULTIPLIER: Number64,
-
-    // Max operations per block
-    MAX_PROPOSER_SLASHINGS: Number64,
-    MAX_ATTESTER_SLASHINGS: Number64,
-    MAX_ATTESTATIONS: Number64,
-    MAX_DEPOSITS: Number64,
-    MAX_VOLUNTARY_EXITS: Number64,
-  },
-  // Expected and container fields are the same here
-  expectedCase: "notransform",
-});
diff --git a/packages/params/src/preset/ssz.ts b/packages/params/src/preset/ssz.ts
deleted file mode 100644
index afbf3c9588b..00000000000
--- a/packages/params/src/preset/ssz.ts
+++ /dev/null
@@ -1,17 +0,0 @@
-/* eslint-disable @typescript-eslint/naming-convention */
-
-import {ContainerType} from "@chainsafe/ssz";
-
-import {IBeaconPreset} from "./interface";
-import {Phase0Preset} from "./phase0";
-import {AltairPreset} from "./altair";
-import {BellatrixPreset} from "./bellatrix";
-
-export const BeaconPreset = new ContainerType<IBeaconPreset>({
-  fields: {
-    ...Phase0Preset.fields,
-    ...AltairPreset.fields,
-    ...BellatrixPreset.fields,
-  },
-  expectedCase: "notransform",
-});
diff --git a/packages/params/src/preset/presetName.ts b/packages/params/src/presetName.ts
similarity index 100%
rename from packages/params/src/preset/presetName.ts
rename to packages/params/src/presetName.ts
diff --git a/packages/params/src/presets/mainnet/altair.ts b/packages/params/src/presets/mainnet/altair.ts
index 04badb8d252..dd1b4f2b7b9 100644
--- a/packages/params/src/presets/mainnet/altair.ts
+++ b/packages/params/src/presets/mainnet/altair.ts
@@ -1,7 +1,7 @@
-/* eslint-disable @typescript-eslint/naming-convention */
-import {IAltairPreset} from "../../preset";
+import {AltairPreset} from "../../interface/altair";
 
-export const altair: IAltairPreset = {
+/* eslint-disable @typescript-eslint/naming-convention */
+export const altair: AltairPreset = {
   SYNC_COMMITTEE_SIZE: 512,
   EPOCHS_PER_SYNC_COMMITTEE_PERIOD: 256,
   INACTIVITY_PENALTY_QUOTIENT_ALTAIR: 50331648,
diff --git a/packages/params/src/presets/mainnet/bellatrix.ts b/packages/params/src/presets/mainnet/bellatrix.ts
index 7e2d146d74e..9923389949e 100644
--- a/packages/params/src/presets/mainnet/bellatrix.ts
+++ b/packages/params/src/presets/mainnet/bellatrix.ts
@@ -1,7 +1,7 @@
-/* eslint-disable @typescript-eslint/naming-convention */
-import {IBellatrixPreset} from "../../preset";
+import {BellatrixPreset} from "../../interface/bellatrix";
 
-export const bellatrix: IBellatrixPreset = {
+/* eslint-disable @typescript-eslint/naming-convention */
+export const bellatrix: BellatrixPreset = {
   INACTIVITY_PENALTY_QUOTIENT_BELLATRIX: 16777216,
   MIN_SLASHING_PENALTY_QUOTIENT_BELLATRIX: 32,
   PROPORTIONAL_SLASHING_MULTIPLIER_BELLATRIX: 3,
diff --git a/packages/params/src/presets/mainnet/index.ts b/packages/params/src/presets/mainnet/index.ts
index 95822b8f849..d2af3ded2d6 100644
--- a/packages/params/src/presets/mainnet/index.ts
+++ b/packages/params/src/presets/mainnet/index.ts
@@ -1,12 +1,11 @@
-import {IBeaconPreset} from "../../preset";
-
 import {phase0} from "./phase0";
 import {altair} from "./altair";
 import {bellatrix} from "./bellatrix";
+import {BeaconPreset} from "../../interface";
 
 export const commit = "v1.1.8";
 
-export const preset: IBeaconPreset = {
+export const preset: BeaconPreset = {
   ...phase0,
   ...altair,
   ...bellatrix,
diff --git a/packages/params/src/presets/mainnet/phase0.ts b/packages/params/src/presets/mainnet/phase0.ts
index 65083f73f39..469499ec7c4 100644
--- a/packages/params/src/presets/mainnet/phase0.ts
+++ b/packages/params/src/presets/mainnet/phase0.ts
@@ -1,9 +1,7 @@
-/* eslint-disable @typescript-eslint/naming-convention */
-// Mainnet preset
-
-import {IPhase0Preset} from "../../preset";
+import {Phase0Preset} from "../../interface/phase0";
 
-export const phase0: IPhase0Preset = {
+/* eslint-disable @typescript-eslint/naming-convention */
+export const phase0: Phase0Preset = {
   // Misc
   // ---------------------------------------------------------------
   // 2**6 (= 64)
@@ -29,7 +27,7 @@ export const phase0: IPhase0Preset = {
   // Gwei values
   // ---------------------------------------------------------------
   // 2**0 * 10**9 (= 1,000,000,000) Gwei
-  MIN_DEPOSIT_AMOUNT: BigInt(1000000000),
+  MIN_DEPOSIT_AMOUNT: 1000000000,
   // 2**5 * 10**9 (= 32,000,000,000) Gwei
   MAX_EFFECTIVE_BALANCE: 32000000000,
   // 2**0 * 10**9 (= 1,000,000,000) Gwei
diff --git a/packages/params/src/presets/mainnet/phase1.ts b/packages/params/src/presets/mainnet/phase1.ts
index 74fa67bfda1..7f255c6ff20 100644
--- a/packages/params/src/presets/mainnet/phase1.ts
+++ b/packages/params/src/presets/mainnet/phase1.ts
@@ -1,6 +1,4 @@
 /* eslint-disable @typescript-eslint/naming-convention */
-
-// Mainnet preset - phase 1
 export const phase1Json = {
   CONFIG_NAME: "mainnet",
 
diff --git a/packages/params/src/presets/minimal/altair.ts b/packages/params/src/presets/minimal/altair.ts
index a2c6ded4726..0c6713ea6a0 100644
--- a/packages/params/src/presets/minimal/altair.ts
+++ b/packages/params/src/presets/minimal/altair.ts
@@ -1,7 +1,7 @@
-/* eslint-disable @typescript-eslint/naming-convention */
-import {IAltairPreset} from "../../preset";
+import {AltairPreset} from "../../interface/altair";
 
-export const altair: IAltairPreset = {
+/* eslint-disable @typescript-eslint/naming-convention */
+export const altair: AltairPreset = {
   SYNC_COMMITTEE_SIZE: 32,
   EPOCHS_PER_SYNC_COMMITTEE_PERIOD: 8,
   INACTIVITY_PENALTY_QUOTIENT_ALTAIR: 50331648,
diff --git a/packages/params/src/presets/minimal/bellatrix.ts b/packages/params/src/presets/minimal/bellatrix.ts
index 7e2d146d74e..9923389949e 100644
--- a/packages/params/src/presets/minimal/bellatrix.ts
+++ b/packages/params/src/presets/minimal/bellatrix.ts
@@ -1,7 +1,7 @@
-/* eslint-disable @typescript-eslint/naming-convention */
-import {IBellatrixPreset} from "../../preset";
+import {BellatrixPreset} from "../../interface/bellatrix";
 
-export const bellatrix: IBellatrixPreset = {
+/* eslint-disable @typescript-eslint/naming-convention */
+export const bellatrix: BellatrixPreset = {
   INACTIVITY_PENALTY_QUOTIENT_BELLATRIX: 16777216,
   MIN_SLASHING_PENALTY_QUOTIENT_BELLATRIX: 32,
   PROPORTIONAL_SLASHING_MULTIPLIER_BELLATRIX: 3,
diff --git a/packages/params/src/presets/minimal/index.ts b/packages/params/src/presets/minimal/index.ts
index 95822b8f849..d2af3ded2d6 100644
--- a/packages/params/src/presets/minimal/index.ts
+++ b/packages/params/src/presets/minimal/index.ts
@@ -1,12 +1,11 @@
-import {IBeaconPreset} from "../../preset";
-
 import {phase0} from "./phase0";
 import {altair} from "./altair";
 import {bellatrix} from "./bellatrix";
+import {BeaconPreset} from "../../interface";
 
 export const commit = "v1.1.8";
 
-export const preset: IBeaconPreset = {
+export const preset: BeaconPreset = {
   ...phase0,
   ...altair,
   ...bellatrix,
diff --git a/packages/params/src/presets/minimal/phase0.ts b/packages/params/src/presets/minimal/phase0.ts
index 65b9640cb55..1e92726784f 100644
--- a/packages/params/src/presets/minimal/phase0.ts
+++ b/packages/params/src/presets/minimal/phase0.ts
@@ -1,9 +1,7 @@
-/* eslint-disable @typescript-eslint/naming-convention */
-// Minimal preset
-
-import {IPhase0Preset} from "../../preset";
+import {Phase0Preset} from "../../interface/phase0";
 
-export const phase0: IPhase0Preset = {
+/* eslint-disable @typescript-eslint/naming-convention */
+export const phase0: Phase0Preset = {
   // Misc
   // ---------------------------------------------------------------
   // [customized] Just 4 committees for slot for testing purposes
@@ -29,7 +27,7 @@ export const phase0: IPhase0Preset = {
   // Gwei values
   // ---------------------------------------------------------------
   // 2**0 * 10**9 (= 1,000,000,000) Gwei
-  MIN_DEPOSIT_AMOUNT: BigInt(1000000000),
+  MIN_DEPOSIT_AMOUNT: 1000000000,
   // 2**5 * 10**9 (= 32,000,000,000) Gwei
   MAX_EFFECTIVE_BALANCE: 32000000000,
   // 2**0 * 10**9 (= 1,000,000,000) Gwei
diff --git a/packages/params/src/presets/minimal/phase1.ts b/packages/params/src/presets/minimal/phase1.ts
index 93173568752..b2bfa8b51be 100644
--- a/packages/params/src/presets/minimal/phase1.ts
+++ b/packages/params/src/presets/minimal/phase1.ts
@@ -1,6 +1,4 @@
 /* eslint-disable @typescript-eslint/naming-convention */
-
-// Minimal preset - phase 1
 export const phase1Json = {
   CONFIG_NAME: "minimal",
 
diff --git a/packages/params/src/setPreset.ts b/packages/params/src/setPreset.ts
index ad78eaf68db..79315263471 100644
--- a/packages/params/src/setPreset.ts
+++ b/packages/params/src/setPreset.ts
@@ -1,4 +1,4 @@
-import {PresetName} from "./preset";
+import {PresetName} from "./presetName";
 import {presetStatus} from "./presetStatus";
 
 export {PresetName};
diff --git a/packages/params/src/utils.ts b/packages/params/src/utils.ts
deleted file mode 100644
index 068449bb966..00000000000
--- a/packages/params/src/utils.ts
+++ /dev/null
@@ -1,18 +0,0 @@
-import {Json} from "@chainsafe/ssz";
-
-import {IBeaconPreset, BeaconPreset} from "./preset";
-
-export function createIBeaconPreset(input: Record<string, unknown>): Partial<IBeaconPreset> {
-  const params: Partial<IBeaconPreset> = {};
-  for (const [fieldName, fieldType] of Object.entries(BeaconPreset.fields)) {
-    if (input[fieldName] != null) {
-      try {
-        (params as Record<string, unknown>)[fieldName] = fieldType.fromJson(input[fieldName] as Json) as unknown;
-      } catch (e) {
-        (e as Error).message = `Error parsing '${fieldName}': ${(e as Error).message}`;
-        throw e;
-      }
-    }
-  }
-  return params;
-}
diff --git a/packages/params/test/e2e/ensure-config-is-synced.test.ts b/packages/params/test/e2e/ensure-config-is-synced.test.ts
index e6792b268aa..a289c2c93f2 100644
--- a/packages/params/test/e2e/ensure-config-is-synced.test.ts
+++ b/packages/params/test/e2e/ensure-config-is-synced.test.ts
@@ -1,14 +1,36 @@
 import {expect} from "chai";
 import axios from "axios";
-import {createIBeaconPreset} from "../../src/utils";
 import * as mainnet from "../../src/presets/mainnet";
 import * as minimal from "../../src/presets/minimal";
-import {ForkName} from "../../src";
+import {ForkName, BeaconPreset} from "../../src";
 import {loadConfigYaml} from "../yaml";
 
 // Not e2e, but slow. Run with e2e tests
 
-async function downloadRemoteConfig(preset: "mainnet" | "minimal", commit: string): Promise<Record<string, unknown>> {
+describe("Ensure config is synced", function () {
+  this.timeout(60 * 1000);
+
+  it("mainnet", async function () {
+    const remotePreset = await downloadRemoteConfig("mainnet", mainnet.commit);
+    assertCorrectPreset({...mainnet.preset}, remotePreset);
+  });
+
+  it("minimal", async function () {
+    const remotePreset = await downloadRemoteConfig("minimal", minimal.commit);
+    assertCorrectPreset({...minimal.preset}, remotePreset);
+  });
+});
+
+function assertCorrectPreset(localPreset: BeaconPreset, remotePreset: BeaconPreset): void {
+  // Check each key for better debuggability
+  for (const key of Object.keys(remotePreset) as (keyof BeaconPreset)[]) {
+    expect(localPreset[key]).to.equal(remotePreset[key], `Wrong ${key} value`);
+  }
+
+  expect(localPreset).to.deep.equal(remotePreset);
+}
+
+async function downloadRemoteConfig(preset: "mainnet" | "minimal", commit: string): Promise<BeaconPreset> {
   const urlByFork: Record<ForkName, string> = {
     [ForkName.phase0]: `https://raw.githubusercontent.com/ethereum/eth2.0-specs/${commit}/presets/${preset}/phase0.yaml`,
     [ForkName.altair]: `https://raw.githubusercontent.com/ethereum/eth2.0-specs/${commit}/presets/${preset}/altair.yaml`,
@@ -23,38 +45,15 @@ async function downloadRemoteConfig(preset: "mainnet" | "minimal", commit: strin
 
   // Merge all the fetched yamls for the different forks
   // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
-  const configParams = Object.assign(...((downloadedParams as unknown) as [input: Record<string, unknown>]));
-
-  return createIBeaconPreset(configParams);
-}
-
-describe("Ensure config is synced", function () {
-  this.timeout(60 * 1000);
+  const beaconPresetRaw: Record<string, unknown> = Object.assign(
+    ...((downloadedParams as unknown) as [input: Record<string, unknown>])
+  );
 
-  // TODO: Remove items from this list as the specs are updated
-  // Items added here are intentionally either not added, or are different
-  // eslint-disable-next-line prettier/prettier
-  const blacklist: string[] = [
-    "SYNC_COMMITTEE_SIZE"
-  ];
+  // As of December 2021 the presets don't include any hex strings
+  const beaconPreset = {} as BeaconPreset;
+  for (const key of Object.keys(beaconPresetRaw)) {
+    beaconPreset[key as keyof BeaconPreset] = parseInt(beaconPresetRaw[key] as string, 10);
+  }
 
-  it("mainnet", async function () {
-    const remotePreset = await downloadRemoteConfig("mainnet", mainnet.commit);
-    const localPreset = {...mainnet.preset};
-    for (const param of blacklist) {
-      delete remotePreset[param];
-      delete (localPreset as Record<string, unknown>)[param];
-    }
-    expect(localPreset).to.deep.equal(remotePreset);
-  });
-
-  it("minimal", async function () {
-    const remotePreset = await downloadRemoteConfig("minimal", minimal.commit);
-    const localPreset = {...minimal.preset};
-    for (const param of blacklist) {
-      delete remotePreset[param];
-      delete (localPreset as Record<string, unknown>)[param];
-    }
-    expect(localPreset).to.deep.equal(remotePreset);
-  });
-});
+  return beaconPreset;
+}
diff --git a/packages/params/test/unit/activePreset.test.ts b/packages/params/test/unit/activePreset.test.ts
index 810751574c9..774a14241f6 100644
--- a/packages/params/test/unit/activePreset.test.ts
+++ b/packages/params/test/unit/activePreset.test.ts
@@ -1,7 +1,8 @@
 import {preset as mainnetParams} from "../../src/presets/mainnet";
 import {preset as minimalParams} from "../../src/presets/minimal";
 import {ACTIVE_PRESET, PresetName} from "../../src";
-import {setActivePreset} from "../../setPreset";
+import {setActivePreset} from "../../src/setPreset";
+import {setActivePreset as setActivePresetLib} from "../../setPreset";
 import {expect} from "chai";
 
 describe("active preset", () => {
@@ -31,7 +32,10 @@ describe("active preset", () => {
 
   it("Should not allow to change preset", () => {
     expect(() => {
+      // I'm not sure if mocha is requiring from src or lib. Each file has different state.
+      // To ensure this throws, call setActivePreset on both the src and lib file.
       setActivePreset(PresetName.minimal);
+      setActivePresetLib(PresetName.minimal);
     }).to.throw();
   });
 });
diff --git a/packages/params/test/unit/constants.test.ts b/packages/types/test/unit/constants.test.ts
similarity index 77%
rename from packages/params/test/unit/constants.test.ts
rename to packages/types/test/unit/constants.test.ts
index 4ce7075adbc..67540b4bc4a 100644
--- a/packages/params/test/unit/constants.test.ts
+++ b/packages/types/test/unit/constants.test.ts
@@ -1,9 +1,13 @@
-import * as constants from "../../src";
-import {ssz} from "@chainsafe/lodestar-types";
+import * as constants from "@chainsafe/lodestar-params";
+import {ssz} from "../../src";
 import {expect} from "chai";
 
 /* eslint-disable @typescript-eslint/naming-convention */
 
+// NOTE: This test is here and not in lodestar-params, to prevent lodestar-params depending on SSZ
+// Since lodestar-params and lodestar-types are in the same mono-repo, running this test here is enough
+// guarantee that these constants are correct.
+
 describe("Lightclient pre-computed constants", () => {
   const FINALIZED_ROOT_GINDEX = Number(ssz.altair.BeaconState.getPathGindex(["finalizedCheckpoint", "root"]));
   const FINALIZED_ROOT_DEPTH = floorlog2(FINALIZED_ROOT_GINDEX);
diff --git a/packages/validator/src/util/params.ts b/packages/validator/src/util/params.ts
index 57e31f8887f..669418c967c 100644
--- a/packages/validator/src/util/params.ts
+++ b/packages/validator/src/util/params.ts
@@ -1,20 +1,18 @@
-import {ChainConfig, IChainConfig} from "@chainsafe/lodestar-config";
+import {IChainConfig, chainConfigToJson} from "@chainsafe/lodestar-config";
 
 export class NotEqualParamsError extends Error {}
 
 /**
- * Assert that two IBeaconParams are identical. Throws error otherwise
+ * Assert localConfig values match externalSpecJson. externalSpecJson may contain more values than localConfig.
  */
-export function assertEqualParams(currentParams: IChainConfig, expectedParams: IChainConfig): void {
-  const params1Json = ChainConfig.toJson(currentParams) as Record<string, unknown>;
-  const params2Json = ChainConfig.toJson(expectedParams) as Record<string, unknown>;
-  const keys = new Set([...Object.keys(params1Json), ...Object.keys(params2Json)]);
+export function assertEqualParams(localConfig: IChainConfig, externalSpecJson: Record<string, string>): void {
+  const params1Json = chainConfigToJson(localConfig) as Record<string, unknown>;
+  const params2Json = externalSpecJson;
 
   const errors: string[] = [];
 
-  for (const key of keys) {
-    if (!params1Json[key]) errors.push(`${key} not in current params`);
-    if (!params2Json[key]) errors.push(`${key} not in expected params`);
+  // Ensure only that the localConfig values match the remote spec
+  for (const key of Object.keys(params1Json)) {
     if (params1Json[key] !== params2Json[key])
       errors.push(`${key} different value: ${params1Json[key]} != ${params2Json[key]}`);
   }
diff --git a/packages/validator/src/validator.ts b/packages/validator/src/validator.ts
index 73883642110..b1e023e8054 100644
--- a/packages/validator/src/validator.ts
+++ b/packages/validator/src/validator.ts
@@ -94,11 +94,13 @@ export class Validator {
     const genesis = await waitForGenesis(api, opts.logger, signal);
     opts.logger.info("Genesis available");
 
-    const {data: nodeParams} = await api.config.getSpec();
-    assertEqualParams(config, nodeParams);
+    const {data: externalSpecJson} = await api.config.getSpec();
+    assertEqualParams(config, externalSpecJson);
     opts.logger.info("Verified node and validator have same config");
+
     await assertEqualGenesis(opts, genesis);
     opts.logger.info("Verified node and validator have same genesisValidatorRoot");
+
     return new Validator(opts, genesis);
   }
 
diff --git a/packages/validator/test/unit/utils/params.test.ts b/packages/validator/test/unit/utils/params.test.ts
index 682bccac22e..2e1ae9c53b0 100644
--- a/packages/validator/test/unit/utils/params.test.ts
+++ b/packages/validator/test/unit/utils/params.test.ts
@@ -1,15 +1,21 @@
-import {createIChainConfig} from "@chainsafe/lodestar-config";
+import {chainConfigToJson} from "@chainsafe/lodestar-config";
 import {chainConfig} from "@chainsafe/lodestar-config/default";
 import {expect} from "chai";
 import {assertEqualParams, NotEqualParamsError} from "../../../src/util/params";
 
 describe("utils / params / assertEqualParams", () => {
   it("default == default", () => {
-    assertEqualParams(chainConfig, chainConfig);
+    const chainConfigJson = chainConfigToJson(chainConfig);
+    assertEqualParams(chainConfig, chainConfigJson);
   });
+
   it("default != other", () => {
+    const chainConfigJson = chainConfigToJson(chainConfig);
+
+    // Force ALTAIR_FORK_EPOCH value to be different
     // eslint-disable-next-line @typescript-eslint/naming-convention
-    const otherConfig = createIChainConfig({...chainConfig, ALTAIR_FORK_EPOCH: 0});
+    const otherConfig = {...chainConfigJson, ALTAIR_FORK_EPOCH: String(chainConfig.ALTAIR_FORK_EPOCH + 1)};
+
     expect(() => assertEqualParams(chainConfig, otherConfig)).to.throw(NotEqualParamsError);
   });
 });