Yojson: JSON library for OCaml

This library parses JSON data into a nested OCaml tree data structure.

Library documentation

Currently at https://ocaml-community.github.io/yojson/

Examples

A simple example on how to parse JSON from a string literal.

let json_string = {|
  {"number" : 42,
   "string" : "yes",
   "list": ["for", "sure", 42]}|}
(* val json_string : string *)

let json = Yojson.Safe.from_string json_string
(* val json : Yojson.Safe.t *)

let () = Format.printf "Parsed to %a" Yojson.Safe.pp json

Related tooling

Yojson is a pretty common choice for parsing JSON in OCaml, as such it is the base for a number of tools and libraries that are built on top of it.

ppx_deriving_yojson to automatically generate code that converts between Yojson.Safe.t and custom OCaml types
ppx_yojson_conv, an alternative to ppx_deriving_yojson from Jane Street with different design decisions
atd, generates mapping code from .atd specification files and can be used in multiple languages
jsonm is an alternate JSON parser that parses JSON into a stream of items, so the complete data structure does not have to be in memory.

Help wanted

Yojson is developed and maintained by volunteers — users like you. Various issues are in need of attention. If you'd like to contribute, please leave a comment on the issue you're interested in, or create a new issue. Experienced contributors will guide you as needed.

There are many simple ways of making a positive impact. For example, you can...

Use the software in your project.
Give a demo to your colleagues.
Share the passion on your blog.
Tweet about what you're doing with Yojson.
Report difficulties by creating new issues. We'll triage them.
Ask questions on StackOverflow.
Answer questions on StackOverflow.
Discuss usage on the OCaml forums.
Pick a task that's easy for you.

Check out in particular good first time issues and other issues with which we could use some help.

License