Relaxed JSON is strict superset JSON, relaxing strictness of vanilla JSON
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Relaxed JSON

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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).
    • 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
  • 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

Related projects

For truly human writable configuration consider using YAML.