diff --git a/src/functionSignatureParser.ts b/src/functionSignatureParser.ts
new file mode 100644
index 0000000..a7615dc
--- /dev/null
+++ b/src/functionSignatureParser.ts
@@ -0,0 +1,63 @@
+import { Method, Variable } from './types'
+
+/**
+ * @description parses code signatures in the format returns[type name,] = namespace.foo([type name,])
+ * @example integer retval, string val = reaper.GetProjExtState(ReaProject proj, string extname, string key)
+ */
+export function parseFunctionEntry(code: string): Method | undefined {
+  const exceptions = ['new_array']
+
+  const rgx = /(?:(?<returns>.+)\s)?(?:(?<namespace>[\w{}.]+)\.)?(?<name>\w+)\((?<params>[^)]+)?\)/
+  const matches = rgx.exec(code)
+  if (matches && matches.groups) {
+    if (exceptions.includes(matches.groups.name)) return
+
+    const method: Method = { name: matches.groups.name }
+
+    if (matches.groups.params) {
+      method.params = separateMandatoryFromOptional(matches.groups.params, 'params')
+    }
+    if (matches.groups.returns) method.returns = parseVariables(matches.groups.returns, 'returns')
+    if (matches.groups.namespace) method.namespace = matches.groups.namespace.trim()
+
+    return method
+  }
+}
+
+function separateMandatoryFromOptional(signature: string, type: 'params' | 'returns'): Variable[] {
+  const rgx = /(?<mandatory>[^[]+)(?:\[(?<optional>.+)])?/
+  const matches = rgx.exec(signature)
+
+  let variables: Variable[] = []
+
+  if (matches && matches.groups) {
+    if (matches.groups.mandatory) {
+      variables = variables.concat(parseVariables(matches.groups.mandatory, type))
+    }
+    if (matches.groups.optional) {
+      const optionals = parseVariables(matches.groups.optional, type)
+      variables = variables.concat(optionals.map((v) => Object.assign(v, { optional: true })))
+    }
+  }
+  return variables
+}
+
+function parseVariables(signature: string, type: 'params' | 'returns'): Variable[] {
+  const chunks = signature.split(',')
+  const rgx = /(\w+)(?:\s+(\w+))?/
+  const variables = chunks
+    .map((c) => {
+      const matches = rgx.exec(c)
+      if (matches && matches.length > 1) {
+        if (matches[2]) {
+          return { type: matches[1], name: matches[2] }
+        } else {
+          if (type === 'params') return { name: matches[1] }
+          if (type === 'returns') return { type: matches[1] }
+        }
+      }
+    })
+    .filter((v) => !!v)
+
+  return variables as Variable[]
+}
diff --git a/src/index.ts b/src/index.ts
index 9d5b02d..acccef1 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -7,3 +7,7 @@ const apiPath = path.resolve(__dirname, '..', 'api', 'reascripthelp.html')
 const apiHTML = fs.readFileSync(apiPath, 'utf8')
 
 const apiJSON = parser(apiHTML)
+
+const outputDir = path.resolve(__dirname, '..', 'output')
+if (!fs.existsSync(outputDir)) fs.mkdirSync(outputDir)
+fs.writeFileSync(path.resolve(outputDir, 'reaperAPI.json'), JSON.stringify(apiJSON))
diff --git a/src/parser.ts b/src/parser.ts
index eec83c0..1ea98ca 100644
--- a/src/parser.ts
+++ b/src/parser.ts
@@ -1,33 +1,30 @@
 import jsdom = require('jsdom')
 
-interface Variable {
-  type?: string
-  name?: string
-}
-
-export interface Method {
-  name: string
-  params?: Variable[]
-  returns?: Variable[]
-  description?: string
-}
+import { Method } from './types'
+import { parseFunctionEntry } from './functionSignatureParser'
 
 export function parser(apiHTML: string): Method[] {
   const { document } = new jsdom.JSDOM(apiHTML).window
 
-  const luaFunctions = document.getElementsByClassName('l_func')
+  const mainMethods = parseLuaFunctions(document.getElementsByClassName('l_func'))
+  const builtIn = parseLuaFunctions(document.getElementsByClassName('l_funcs'))
+  return mainMethods.concat(builtIn)
+}
 
+function parseLuaFunctions(luaFunctions: HTMLCollection): Method[] {
   const methods: Method[] = []
   for (let i = 0; i < luaFunctions.length; i++) {
-    const fEntries = luaFunctions[i].getElementsByTagName('code')
-    if (fEntries.length != 1) continue
-    const entry = fEntries[0]
-
-    const method = parseFunctionEntry(entry)
-    if (method) {
-      const description = lookForDescription(luaFunctions[i])
-      if (description) method.description = description
-      methods.push(method)
+    const codes = luaFunctions[i].getElementsByTagName('code')
+    for (let j = 0; j < codes.length; j++) {
+      if (!codes[j] || !codes[j].textContent) continue
+      const m = parseFunctionEntry(<string>codes[j].textContent)
+      if (m) {
+        // determines whether it's parsing built in functions or main api in order to look for description in right branch
+        const siblingOfDescription = codes.length > 1 ? codes[j] : luaFunctions[i]
+        const description = lookForDescription(siblingOfDescription)
+        if (description) m.description = description
+        methods.push(m)
+      }
     }
   }
 
@@ -37,71 +34,16 @@ export function parser(apiHTML: string): Method[] {
 function lookForDescription(node: Element): string {
   let currNode: ChildNode | null = node.nextSibling
 
+  let description = ''
   while (currNode) {
     if (currNode.nodeName !== '#text') {
       if (currNode.nodeName == 'A') break
     } else {
       if (currNode.textContent && /\w+/.test(currNode.textContent)) {
-        return currNode.textContent.trim()
+        description = description + currNode.textContent.trim() + '\n'
       }
     }
     currNode = currNode.nextSibling
   }
-  return ''
-}
-
-function parseFunctionEntry(node: HTMLElement): Method | undefined {
-  const nodes: Node[] = []
-
-  for (let i = 0; i < node.childNodes.length; i++) {
-    nodes.push(node.childNodes[i])
-  }
-
-  if (
-    nodes.some(
-      (n) => !(n.nodeName === '#text' || n.nodeName === 'I') || typeof n.textContent !== 'string'
-    )
-  ) {
-    return
-  }
-
-  const nameI = nodes.findIndex((n) => /reaper\./.test(<string>n.textContent))
-  if (nameI < 0) return
-
-  const nameMatches = /reaper\.([^(]+)/.exec(<string>nodes[nameI].textContent)
-  if (!nameMatches || !nameMatches[1]) return
-
-  const method: Method = { name: nameMatches[1] }
-
-  const returns = parseVariables(nodes.slice(0, nameI + 1))
-  const params = parseVariables(nodes.slice(nameI, nodes.length))
-
-  if (returns.length > 0) method.returns = returns
-  if (params.length > 0) method.params = params
-
-  return method
-}
-
-function parseVariables(nodes: Node[]): Variable[] {
-  const vars: Variable[] = []
-
-  nodes.forEach((n) => {
-    const text = n.textContent?.trim()
-    if (!text) return
-
-    const textMatches = /\w+/.exec(text)
-
-    if (textMatches && textMatches[0] && n.nodeName === 'I') vars.push({ type: textMatches[0] })
-    if (
-      textMatches &&
-      textMatches[0] &&
-      n.nodeName === '#text' &&
-      vars[vars.length - 1] &&
-      !/reaper\./.test(textMatches[0])
-    ) {
-      vars[vars.length - 1].name = textMatches[0]
-    }
-  })
-
-  return vars
+  return description.trim()
 }
diff --git a/src/types.ts b/src/types.ts
new file mode 100644
index 0000000..ceea4fb
--- /dev/null
+++ b/src/types.ts
@@ -0,0 +1,13 @@
+export interface Variable {
+  type?: string
+  name?: string
+  optional?: boolean
+}
+
+export interface Method {
+  name: string
+  params?: Variable[]
+  returns?: Variable[]
+  description?: string
+  namespace?: string
+}