package yojson

  1. Overview
  2. Docs
Yojson is an optimized parsing and printing library for the JSON format

Install 

dune-project
 Dependency

github.com Readme Changelog BSD-3-Clause License Edit opam file Versions (15)

Authors

  1. M
    Martin Jambon

Maintainers

  1. P
    paul-elliot@tarides.com
  2. N
    nathan@tarides.com
  3. M
    marek@tarides.com

Sources

yojson-3.0.0.tbz
sha256=99414da7609b92a02474ef4b49ecda15edc8cbba5229341b124e7e4695c39610
sha512=896d0ea829a36ccadba6628800369c1a3ab9e7c64dbda8b76331889c9db481cd64e137f467481ae80a8dd5fca45d748bfa71f58641806cc1bb1a007f8291789f

Description

Yojson is an optimized parsing and printing library for the JSON format.

ydump is a pretty-printing command-line program provided with the yojson package.

Published: 02 Jun 2025

README

Yojson: JSON library for OCaml

Build Status

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

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

Yojson is licensed under the 3-clause BSD license, see LICENSE.md for details.

Dependencies (2)

  1. ocaml >= "4.08"
  2. dune >= "2.7"

Dev Dependencies (2)

  1. odoc with-doc
  2. alcotest with-test & >= "0.8.5"

  1. 0install >= "2.18"
  2. abella >= "2.0.8"
  3. acgtk
  4. anthropic
  5. archetype
  6. atd >= "2.6.0"
  7. atdgen-runtime >= "2.10.0"
  8. avro-compiler
  9. aws-config
  10. aws-s3 < "4.5.1" | >= "4.8.0"
  11. awsm-codegen
  12. bap-radare2
  13. bitcoin >= "3.0"
  14. boulangerie
  15. builder-web >= "0.2.0"
  16. caisar
  17. calculon != "0.5"
  18. calculon-redis-lib
  19. calculon-web = "0.6"
  20. camelot >= "1.3.0"
  21. camels
  22. canary
  23. catala = "0.9.0"
  24. cb-check
  25. cbor >= "0.3"
  26. cconv-ppx
  27. chess_com_api
  28. colibrics
  29. comby-semantic
  30. commons
  31. containers >= "3.9"
  32. coq-lsp
  33. coq-of-ocaml
  34. coq-serapi >= "8.10.0+0.7.0" & < "8.20.0+0.20.0"
  35. crs >= "0.0.20250705"
  36. current_docker
  37. current_examples
  38. current_git
  39. current_github
  40. current_gitlab
  41. current_slack
  42. current_ssh
  43. current_web
  44. dap
  45. daypack-lib
  46. dblp-api
  47. decoders-yojson >= "0.7.0"
  48. devkit
  49. docfd >= "2.1.0"
  50. docker-api >= "0.2.2"
  51. docker_hub
  52. dot-merlin-reader < "4.9"
  53. dream
  54. dream-inertia
  55. dune-cargo-build
  56. dune-release >= "1.4.0"
  57. dune_deps_extra
  58. eio_main >= "0.10"
  59. elasticsearch-cli = "0.5"
  60. elpi >= "3.3.1"
  61. fiat-p256
  62. fit >= "1.2.0"
  63. forester >= "3.1.0"
  64. frama-c < "23.0" | >= "27.0~beta"
  65. fred
  66. frenetic
  67. fstar
  68. gapi-ocaml
  69. gdbprofiler
  70. gemini
  71. gendarme-json
  72. github != "4.0.0"
  73. github-data
  74. gitlab
  75. goblint-cil >= "1.8.0"
  76. gopcaml-mode-merlin < "0.0.6"
  77. gradescope_submit
  78. graphql < "0.9.0" | >= "0.14.0"
  79. graphql-async >= "0.14.0"
  80. graphql-cohttp >= "0.13.0"
  81. graphql-lwt >= "0.14.0"
  82. graphql_ppx
  83. gremlin
  84. guardian
  85. h2
  86. hacl_x25519
  87. hilite < "0.3.0"
  88. hl_yaml
  89. hockmd
  90. horned_worm
  91. hpack
  92. hsluv
  93. httph
  94. index-bench
  95. ip2location
  96. ip2locationio
  97. ip2whois
  98. irmin-graphql
  99. irmin-tezos
  100. jasmin
  101. jhupllib
  102. jose
  103. js_of_ocaml-compiler
  104. jsonschema
  105. jsonschema2atd
  106. jupyter
  107. jupyter-kernel
  108. jwto
  109. kappa-library < "4.1.3"
  110. karamel
  111. kremlin < "transition"
  112. kubecaml
  113. lablgtk3-extras >= "3.0.1"
  114. lambdapi
  115. learn-ocaml
  116. letsencrypt
  117. letters
  118. libsail
  119. lichess_api
  120. linol >= "0.2" & < "0.10"
  121. linol-eio
  122. linol-lwt
  123. lockfree >= "0.3.1"
  124. logs-async-reporter >= "1.3"
  125. lsp < "1.6.0"
  126. melange-json = "1.2.0"
  127. melange-json-native
  128. merlin != "4.5-411"
  129. metadb
  130. mirage-crypto-ec
  131. mjson
  132. monorobot
  133. mopsa
  134. morbig >= "0.11.0"
  135. multicore-bench
  136. mutaml
  137. nloge
  138. nsq
  139. obuilder
  140. ocaml-lsp-server < "1.10.5" | >= "1.18.0" & != "1.21.0-4.14" & < "1.23.0"
  141. ocaml-protoc-plugin >= "6.1.0"
  142. ocaml_db_model
  143. ocaml_pgsql_model
  144. ocamleditor >= "1.15.2-ocaml414"
  145. ocsigen-start
  146. odoc >= "3.0.0"
  147. odoc-driver
  148. oframl
  149. oidc
  150. ojs-base
  151. ojs_base
  152. ometrics < "0.2.0"
  153. openai-gym
  154. openapi
  155. openapi_router
  156. opencage
  157. openstellina
  158. opium >= "0.19.0"
  159. oraft
  160. orun
  161. osh
  162. ozulip
  163. pa_ppx < "0.14" | >= "0.19"
  164. pandoc
  165. pbrt_yojson
  166. pds-reachability >= "0.2.3"
  167. petr4
  168. pgn_parser
  169. phylogenetics >= "0.2.0"
  170. piece_rope
  171. pkcs11-driver >= "1.0.0"
  172. ppx_deriving_jsonschema
  173. ppx_deriving_yojson < "3.6.1"
  174. ppx_protocol_conv_json < "5.0.0" | >= "5.2.1"
  175. ppx_yojson
  176. ppx_yojson_conv < "v0.13.0"
  177. ppx_yojson_conv_lib
  178. prof_spacetime
  179. qmp >= "0.19.0"
  180. quests
  181. r2pipe
  182. radare2
  183. rdf
  184. records = "0.6.0" | >= "1.0.0"
  185. repr-bench
  186. rpclib
  187. rungen
  188. rust-staticlib-gen
  189. SZXX
  190. safemoney
  191. sail < "0.15"
  192. saturn
  193. saturn_lockfree
  194. satyrographos != "0.0.2.7" & < "0.0.2.13"
  195. savvy
  196. semver2
  197. serde_json
  198. sihl < "0.2.0" | >= "0.3.0~rc2"
  199. sihl-core
  200. slack
  201. slug
  202. smaws-lib
  203. smtml >= "0.7.0"
  204. snf_mcp < "0.2.1"
  205. spotify-web-api
  206. starred_ml
  207. swagger
  208. tdigest < "2.1.0"
  209. textmate-language >= "0.3.4"
  210. textrazor >= "0.1.1"
  211. tezos-context-hash-irmin
  212. tidy_email_sendgrid
  213. timedesc < "0.8.0"
  214. timedesc-json
  215. timere < "0.4.0"
  216. user-agent-parser
  217. vecosek
  218. vercel
  219. vscoq-language-server
  220. vsrocq-language-server
  221. wasm_of_ocaml-compiler
  222. webauthn
  223. why3find
  224. xapi-rrd >= "1.9.0"
  225. yojson-five >= "3.0.0"
  226. yosqlite >= "0.2"
  227. zanuda
  228. zarr

Conflicts

None