diff --git a/apps/repl/app/components/limber/github.gts b/apps/repl/app/components/limber/github.gts
new file mode 100644
index 000000000..340f57925
--- /dev/null
+++ b/apps/repl/app/components/limber/github.gts
@@ -0,0 +1,26 @@
+import { on } from '@ember/modifier';
+
+import { service } from 'ember-primitives';
+
+import type EditorService from 'limber/services/editor';
+
+function getAuth(editor: EditorService) {
+  return editor.auth;
+}
+
+export const GitHubLogin = <template>
+  {{#let (getAuth (service 'editor')) as |auth|}}
+    {{#if auth.isPending}}
+      ...
+    {{else if auth.isAuthenticated}}
+      Logged in
+      <button {{on 'click' auth.logout}}>
+        Logout
+      </button>
+    {{else}}
+      <button {{on 'click' auth.login}}>
+        Login with GitHub
+      </button>
+    {{/if}}
+  {{/let}}
+</template>;
diff --git a/apps/repl/app/components/limber/header.gts b/apps/repl/app/components/limber/header.gts
index 77e155f5f..a4e8e9d14 100644
--- a/apps/repl/app/components/limber/header.gts
+++ b/apps/repl/app/components/limber/header.gts
@@ -2,6 +2,7 @@ import FaIcon from '@fortawesome/ember-fontawesome/components/fa-icon';
 
 import ExternalLink from '../external-link';
 import DemoSelect from './demo-select';
+import { GitHubLogin } from './github';
 
 <template>
   <header
@@ -21,6 +22,7 @@ import DemoSelect from './demo-select';
     </h1>
 
     <nav class='text-white mt-1 flex gap-2 items-baseline'>
+      <GitHubLogin />
 
       <DemoSelect />
 
diff --git a/apps/repl/app/routes/application.ts b/apps/repl/app/routes/application.ts
index 1fc5df066..ad4680e88 100644
--- a/apps/repl/app/routes/application.ts
+++ b/apps/repl/app/routes/application.ts
@@ -2,11 +2,18 @@
 // @ts-ignore
 import { DEBUG } from '@glimmer/env';
 import Route from '@ember/routing/route';
+import { service } from '@ember/service';
 
 import { notInIframe } from 'limber/helpers/in-iframe';
 
+import type EditorService from 'limber/services/editor';
+
 export default class ApplicationRoute extends Route {
+  @service declare editor: EditorService;
+
   async beforeModel() {
+    await this.editor.auth.check();
+
     document.querySelector('#initial-loader')?.remove();
 
     if (DEBUG) {
diff --git a/apps/repl/app/services/editor.ts b/apps/repl/app/services/editor.ts
index 8be2982c0..e246acac9 100644
--- a/apps/repl/app/services/editor.ts
+++ b/apps/repl/app/services/editor.ts
@@ -4,6 +4,7 @@ import Service, { inject as service } from '@ember/service';
 
 import { link } from 'ember-resources/link';
 
+import { Auth0 } from 'limber/utils/auth';
 import { FileURIComponent } from 'limber/utils/editor-text';
 
 import type RouterService from '@ember/routing/router-service';
@@ -18,6 +19,7 @@ export default class EditorService extends Service {
   @tracked scrollbarWidth = 0;
 
   @link(FileURIComponent) declare fileURIComponent: FileURIComponent;
+  @link(Auth0) declare auth: Auth0;
 
   @action
   updateText(text: string) {
diff --git a/apps/repl/app/utils/auth.ts b/apps/repl/app/utils/auth.ts
new file mode 100644
index 000000000..b7ea44cb2
--- /dev/null
+++ b/apps/repl/app/utils/auth.ts
@@ -0,0 +1,72 @@
+import { tracked } from '@glimmer/tracking';
+
+import type { Auth0Client } from '@auth0/auth0-spa-js';
+
+export class Auth0 {
+  #client: Auth0Client | null = null;
+
+  constructor() {
+    this.#setup();
+  }
+
+  @tracked isAuthenticated: boolean | null = null;
+
+  get isPending() {
+    return this.isAuthenticated === null;
+  }
+
+  #setup = async () => {
+    if (this.#client) return this.#client;
+
+    const { createAuth0Client } = await import('@auth0/auth0-spa-js');
+
+    this.#client = await createAuth0Client({
+      domain: 'glimdown.us.auth0.com',
+      clientId: 'QwKnvGVl1KzoVAuBGc8WYSReeNXahvv2',
+    });
+
+    await this.#updateAuthStatus();
+
+    return this.#client;
+  };
+
+  #updateAuthStatus = async () => {
+    if (!this.#client) return;
+
+    let status = await this.#client.isAuthenticated();
+
+    this.isAuthenticated = status;
+
+    return this.isAuthenticated;
+  };
+
+  check = async () => {
+    await this.#setup();
+    await this.#updateAuthStatus();
+  };
+
+  login = async () => {
+    let client = await this.#setup();
+
+    if (this.isAuthenticated) return;
+
+    await client.loginWithPopup();
+    await this.#updateAuthStatus();
+  };
+
+  /**
+   * Auth0 should make this easier...
+   * - https://community.auth0.com/t/is-login-via-auth0-possible-without-reloading-my-spa/18846
+   * - https://community.auth0.com/t/auth0js-logout-without-redirect/23966/2
+   * - https://community.auth0.com/t/how-to-logout-without-reload/100289
+   */
+  logout = async () => {
+    await this.#setup();
+
+    if (!this.isAuthenticated) return;
+
+    document.cookie = '';
+    this.#client = null;
+    await this.#setup();
+  };
+}
diff --git a/apps/repl/config/environment.js b/apps/repl/config/environment.js
index 690329124..df7a298b2 100644
--- a/apps/repl/config/environment.js
+++ b/apps/repl/config/environment.js
@@ -1,20 +1,6 @@
 'use strict';
 
-const fs = require('fs');
-const path = require('path');
-
-function ref() {
-  const rev = fs.readFileSync(path.join(__dirname, '../../../.git/HEAD')).toString().trim();
-
-  if (rev.indexOf(':') === -1) {
-    return rev;
-  } else {
-    return fs
-      .readFileSync(path.join(__dirname, '../../../.git/' + rev.substring(5)))
-      .toString()
-      .trim();
-  }
-}
+const { refAbbr } = require('@glimdown/app-node-support/git');
 
 module.exports = function (environment) {
   let ENV = {
@@ -34,7 +20,7 @@ module.exports = function (environment) {
     },
 
     APP: {
-      version: `REPL :: ${ref()} :: ${new Date()}`,
+      version: `REPL :: ${refAbbr()} :: ${new Date()}`,
       // Here you can pass flags/options to your application instance
       // when it is created
     },
diff --git a/apps/repl/package.json b/apps/repl/package.json
index f06ab56a3..88f975262 100644
--- a/apps/repl/package.json
+++ b/apps/repl/package.json
@@ -54,6 +54,7 @@
     "@fortawesome/free-brands-svg-icons": "^6.4.2",
     "@fortawesome/free-regular-svg-icons": "^6.4.2",
     "@fortawesome/free-solid-svg-icons": "^6.4.2",
+    "@glimdown/app-node-support": "workspace:*",
     "@glint/core": "^1.0.2",
     "@glint/environment-ember-loose": "^1.0.2",
     "@glint/environment-ember-template-imports": "^1.0.2",
@@ -132,6 +133,7 @@
     "extends": "../../package.json"
   },
   "dependencies": {
+    "@auth0/auth0-spa-js": "^2.1.1",
     "@ember/test-waiters": "^3.0.2",
     "@embroider/macros": "1.13.1",
     "@embroider/router": "2.1.3",
diff --git a/packages/app-support/node/.eslintignore b/packages/app-support/node/.eslintignore
new file mode 100644
index 000000000..e99befd13
--- /dev/null
+++ b/packages/app-support/node/.eslintignore
@@ -0,0 +1,7 @@
+dist/
+node_modules/
+tmp/
+vendor/
+public/
+coverage/
+*.ember-try
diff --git a/packages/app-support/node/.eslintrc.cjs b/packages/app-support/node/.eslintrc.cjs
new file mode 100644
index 000000000..dba2f3b5c
--- /dev/null
+++ b/packages/app-support/node/.eslintrc.cjs
@@ -0,0 +1,10 @@
+'use strict';
+
+const { configs } = require('@nullvoxpopuli/eslint-configs');
+
+const config = configs.node();
+
+module.exports = {
+  ...config,
+  overrides: [...config.overrides],
+};
diff --git a/packages/app-support/node/.prettierignore b/packages/app-support/node/.prettierignore
new file mode 100644
index 000000000..2c2166f4b
--- /dev/null
+++ b/packages/app-support/node/.prettierignore
@@ -0,0 +1,13 @@
+*.yml
+*.yaml
+*.md
+*.json
+renovate.json5
+docs/
+
+node_modules/
+dist/
+public/
+vendor/
+coverage/
+.lint-todo/
diff --git a/packages/app-support/node/.prettierrc.cjs b/packages/app-support/node/.prettierrc.cjs
new file mode 100644
index 000000000..4a70f1981
--- /dev/null
+++ b/packages/app-support/node/.prettierrc.cjs
@@ -0,0 +1,35 @@
+'use strict';
+
+module.exports = {
+  printWidth: 100,
+  overrides: [
+    {
+      // Lol, JavaScript
+      files: ['*.js', '*.ts', '*.cjs', '.mjs', '.cts', '.mts', '.cts'],
+      options: {
+        singleQuote: true,
+        trailingComma: 'es5',
+      },
+    },
+    {
+      files: ['*.json'],
+      options: {
+        singleQuote: false,
+      },
+    },
+    {
+      files: ['**/*.hbs'],
+      options: {
+        singleQuote: false,
+      },
+    },
+    {
+      files: ['**/*.gjs', '**/*.gts'],
+      options: {
+        singleQuote: true,
+        trailingComma: 'es5',
+      },
+      plugins: ['prettier-plugin-ember-template-tag'],
+    },
+  ],
+};
diff --git a/packages/app-support/node/package.json b/packages/app-support/node/package.json
new file mode 100644
index 000000000..ef05e90b2
--- /dev/null
+++ b/packages/app-support/node/package.json
@@ -0,0 +1,41 @@
+{
+  "name": "@glimdown/app-node-support",
+  "private": true,
+  "type": "module",
+  "license": "MIT",
+  "author": "NullVoxPopuli",
+  "exports": {
+    "./git": "./src/git.cjs"
+  },
+  "scripts": {
+    "lint:fix": "pnpm -w exec lint fix",
+    "build": "tailwindcss -o dist/tailwind.css",
+    "start": "tailwindcss -o dist/tailwind.css --watch",
+    "lint": "pnpm -w exec lint",
+    "lint:js": "pnpm -w exec lint js",
+    "lint:js:fix": "pnpm -w exec lint js:fix",
+    "lint:prettier:fix": "pnpm -w exec lint prettier:fix",
+    "lint:prettier": "pnpm -w exec lint prettier"
+  },
+  "devDependencies": {
+    "@babel/core": "^7.22.9",
+    "@nullvoxpopuli/eslint-configs": "^3.2.0",
+    "concurrently": "^8.2.0",
+    "eslint": "^8.45.0",
+    "prettier": "^2.8.8",
+    "prettier-plugin-ember-template-tag": "^1.0.0"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/NullVoxPopuli/limber.git",
+    "directory": "packages/app-support/node"
+  },
+  "engines": {
+    "node": ">= v16",
+    "npm": "use pnpm",
+    "yarn": "use pnpm"
+  },
+  "volta": {
+    "extends": "../../../package.json"
+  }
+}
diff --git a/packages/app-support/node/src/git.cjs b/packages/app-support/node/src/git.cjs
new file mode 100644
index 000000000..b72778e2e
--- /dev/null
+++ b/packages/app-support/node/src/git.cjs
@@ -0,0 +1,34 @@
+const { spawnSync } = require('child_process');
+
+function currentCommitSHA() {
+  const result = spawnSync('git', ['rev-parse', 'HEAD'], { encoding: 'utf-8' });
+
+  if (result.error) {
+    throw result.error;
+  }
+
+  if (result.status !== 0) {
+    throw new Error(`Git command failed with status ${result.status}: ${result.stderr}`);
+  }
+
+  return result.stdout.trim();
+}
+function currentGitBranch() {
+  const result = spawnSync('git', ['rev-parse', '--abbrev-ref', 'HEAD'], { encoding: 'utf-8' });
+
+  if (result.error) {
+    throw result.error;
+  }
+
+  if (result.status !== 0) {
+    throw new Error(`Git command failed with status ${result.status}: ${result.stderr}`);
+  }
+
+  return result.stdout.trim();
+}
+
+function refAbbr() {
+  return `${currentGitBranch()} :: ${currentCommitSHA()}`;
+}
+
+module.exports = { currentCommitSHA, currentGitBranch, refAbbr };
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 2ebde1974..318e46cab 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -69,6 +69,9 @@ importers:
 
   apps/repl:
     dependencies:
+      '@auth0/auth0-spa-js':
+        specifier: ^2.1.1
+        version: 2.1.1
       '@ember/test-waiters':
         specifier: ^3.0.2
         version: 3.0.2
@@ -244,6 +247,9 @@ importers:
       '@fortawesome/free-solid-svg-icons':
         specifier: ^6.4.2
         version: 6.4.2
+      '@glimdown/app-node-support':
+        specifier: workspace:*
+        version: link:../../packages/app-support/node
       '@glint/core':
         specifier: ^1.0.2
         version: 1.0.2(typescript@5.1.6)
@@ -1120,6 +1126,27 @@ importers:
         specifier: ^5.88.2
         version: 5.88.2
 
+  packages/app-support/node:
+    devDependencies:
+      '@babel/core':
+        specifier: ^7.22.9
+        version: 7.22.9(supports-color@8.1.1)
+      '@nullvoxpopuli/eslint-configs':
+        specifier: ^3.1.3
+        version: 3.1.3(@babel/core@7.22.9)(eslint@8.45.0)(prettier@2.8.8)
+      concurrently:
+        specifier: ^8.2.0
+        version: 8.2.0
+      eslint:
+        specifier: ^8.45.0
+        version: 8.45.0
+      prettier:
+        specifier: ^2.8.8
+        version: 2.8.8
+      prettier-plugin-ember-template-tag:
+        specifier: ^1.0.0
+        version: 1.0.0(prettier@2.8.8)
+
   packages/app-support/styles:
     dependencies:
       '@tailwindcss/typography':
@@ -2507,6 +2534,10 @@ packages:
       '@jridgewell/gen-mapping': 0.3.3
       '@jridgewell/trace-mapping': 0.3.18
 
+  /@auth0/auth0-spa-js@2.1.1:
+    resolution: {integrity: sha512-21qEf5Bjouy76CWd1gQgf/tT6iD513YFYaK0+3OF1nbwLtPFpxm5Ln94M7SCVFKfe5jbchWuEcIb1HLer3r6RA==}
+    dev: false
+
   /@babel/code-frame@7.22.5:
     resolution: {integrity: sha512-Xmwn266vad+6DAqEB2A6V/CcZVp62BbwVmcOJc2RPuwih1kw02TjQvWVWlcKGbBPd+8/0V5DEkOcizRGYsspYQ==}
     engines: {node: '>=6.9.0'}
@@ -2625,7 +2656,7 @@ packages:
       '@babel/helper-plugin-utils': 7.22.5
       debug: 4.3.4(supports-color@8.1.1)
       lodash.debounce: 4.0.8
-      resolve: 1.22.2
+      resolve: 1.22.3
     transitivePeerDependencies:
       - supports-color
 
@@ -8110,7 +8141,7 @@ packages:
     dependencies:
       '@babel/runtime': 7.22.6
       cosmiconfig: 6.0.0
-      resolve: 1.22.2
+      resolve: 1.22.3
     dev: false
 
   /babel-plugin-module-resolver@3.2.0:
@@ -9097,7 +9128,7 @@ packages:
       ensure-posix-path: 1.1.1
       fs-extra: 8.1.0
       minimatch: 3.1.2
-      resolve: 1.22.2
+      resolve: 1.22.3
       rsvp: 4.8.5
       symlink-or-copy: 1.3.1
       walk-sync: 1.1.4
@@ -12320,7 +12351,7 @@ packages:
     dependencies:
       debug: 3.2.7
       is-core-module: 2.12.1
-      resolve: 1.22.2
+      resolve: 1.22.3
     transitivePeerDependencies:
       - supports-color
     dev: true
@@ -12602,7 +12633,7 @@ packages:
       ignore: 5.2.4
       is-core-module: 2.12.1
       minimatch: 3.1.2
-      resolve: 1.22.2
+      resolve: 1.22.3
       semver: 7.5.4
     dev: true
 
@@ -12798,7 +12829,7 @@ packages:
     dependencies:
       acorn: 8.10.0
       acorn-walk: 8.2.0
-      resolve: 1.22.2
+      resolve: 1.22.3
       serve-static: 1.15.0
     transitivePeerDependencies:
       - supports-color
@@ -16829,7 +16860,7 @@ packages:
     resolution: {integrity: sha512-/5CMN3T0R4XTj4DcGaexo+roZSdSFW/0AOOTROrjxzCG1wrWXEsGbRKevjlIL+ZDE4sZlJr5ED4YW0yqmkK+eA==}
     dependencies:
       hosted-git-info: 2.8.9
-      resolve: 1.22.2
+      resolve: 1.22.3
       semver: 5.7.2
       validate-npm-package-license: 3.0.4
     dev: true
@@ -18542,14 +18573,14 @@ packages:
     resolution: {integrity: sha512-fVEKHGeK85bGbVFuwO9o1aU0n3vqQGrezPc51JGu9UTXpFQfWq5qCeKxyaRUSvephs+06c5j5rPq/dzHGEo8+Q==}
     dependencies:
       path-root: 0.1.1
-      resolve: 1.22.2
+      resolve: 1.22.3
 
   /resolve-package-path@2.0.0:
     resolution: {integrity: sha512-/CLuzodHO2wyyHTzls5Qr+EFeG6RcW4u6//gjYvUfcfyuplIX1SSccU+A5A9A78Gmezkl3NBkFAMxLbzTY9TJA==}
     engines: {node: 8.* || 10.* || >= 12}
     dependencies:
       path-root: 0.1.1
-      resolve: 1.22.2
+      resolve: 1.22.3
 
   /resolve-package-path@3.1.0:
     resolution: {integrity: sha512-2oC2EjWbMJwvSN6Z7DbDfJMnD8MYEouaLn5eIX0j8XwPsYCVIyY9bbnX88YHVkbr8XHqvZrYbxaLPibfTYKZMA==}
@@ -18595,7 +18626,6 @@ packages:
       is-core-module: 2.12.1
       path-parse: 1.0.7
       supports-preserve-symlinks-flag: 1.0.0
-    dev: true
 
   /responselike@1.0.2:
     resolution: {integrity: sha512-/Fpe5guzJk1gPqdJLJR5u7eG/gNY4nImjbRDaVWVMRhne55TCmj2i9Q+54PBRfatRC8v/rIiv9BN0pMd9OV5EQ==}