Are you frustrated that you cannot add comments into your configuration JSON Relaxed JSON is a simple solution. Small JavaScript library with only one exposed function RJSON.transform(text : string) : string (and few convenient helpers).

Relaxed JSON (modified BSD license) is a strict superset of JSON, relaxing strictness of vanilla JSON. Valid, vanilla JSON will not be changed by RJSON.transform. But there are few additional features helping writing JSON by hand.

• Comments are stripped : // foo and /* bar */ → . Comments are converted into whitespace, so your formatting is preserved.
• Trailing comma is allowed : [1, 2, 3, ] → [1, 2, 3]. Works also in objects { "foo": "bar", } → { "foo": "bar" }.
• Identifiers are transformed into strings : { foo: bar } → { "foo": "bar" }.
• Single quoted strings are allowed : 'say "Hello"' → "say \"Hello\"".
• More different characters is supported in identifiers: foo-bar → "foo-bar".

• RJSON.transform(text : string) : string. Transforms Relaxed JSON text into JSON text. Doesn't verify (parse) the JSON, i.e result JSON might be invalid as well
• RJSON.parse(text : string, reviver : function | opts : obj) : obj. Parse the RJSON text, virtually JSON.parse(JSON.transform(text), reviver). You could pass a reviver function or an options object as the second argument. Supported options:
  • reviver: you could still pass a reviver
  • relaxed: use relaxed version of JSON (default: true)
  • warnings: use relaxed JSON own parser, supports better error messages (default: false)
  • tolerant: wait until the end to throw errors
  • duplicate: fail if there are duplicate keys in objects

There is rjson executable^†

$ sudo npm install -g relaxed-json

$ rjson relaxed-json.js
Error on line 27: Unexpected character: (
(function () {

% rjson package.json
{
  "name": "relaxed-json",
  "description": "Relaxed JSON is strict superset JSON, relaxing strictness of valilla JSON",

^†rjson is similar to python -mjson.tool.

• 1.0.1 — 2017-03-08 — Meteor compatibility
  • #9 #14 #15
• 1.0.0 — 2015-07-13 — Stable release
  • Forward slashes bug fixed
• 0.2.9 Dependencies bump
• 0.2.8 Dev dependencies update
• 0.2.7 rjson executable
  • also depedencies update
  • jscs style check
• 0.2.6 Dependencies update
• 0.2.5 Use make
• 0.2.4 Maintenance release
• 0.2.3 Bugfixes
  • $ is valid identifier character
  • single line comments may end with CR and CRLF also
• 0.2.2 Bugfix
• 0.2.1 Code reogranization
  • More though into toleration, handles valid json without colons and commas
  • trailing comma stripping is more strict
• 0.2.0 Shiny new features
  • overloaded rjson.parse
  • tolerating parser support
  • duplicate key warning
  • test suite (!)
• 0.1.1 RJSON.parse
• 0.1.0 Initial release

• strip-json-comments

For truly human writable configuration consider using YAML.

• js-yaml