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. beluga >= "1.1"
  14. bitcoin >= "3.0"
  15. boulangerie
  16. builder-web >= "0.2.0"
  17. caisar
  18. calculon != "0.5"
  19. calculon-redis-lib
  20. calculon-web = "0.6"
  21. camelot >= "1.3.0"
  22. camels
  23. canary
  24. catala = "0.9.0"
  25. cb-check
  26. cbor >= "0.3"
  27. cconv-ppx
  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. fiat-p256
  61. fit >= "1.2.0"
  62. forester >= "3.1.0"
  63. frama-c < "23.0" | >= "27.0~beta"
  64. fred
  65. frenetic
  66. fstar
  67. gapi-ocaml
  68. gdbprofiler
  69. gemini
  70. gendarme-json
  71. github != "4.0.0"
  72. github-data
  73. gitlab
  74. goblint-cil >= "1.8.0"
  75. gopcaml-mode-merlin < "0.0.6"
  76. gradescope_submit
  77. graphql < "0.9.0" | >= "0.14.0"
  78. graphql-async >= "0.14.0"
  79. graphql-cohttp >= "0.13.0"
  80. graphql-lwt >= "0.14.0"
  81. graphql_ppx
  82. gremlin
  83. guardian
  84. h2
  85. hacl_x25519
  86. hilite < "0.3.0"
  87. hl_yaml
  88. hockmd
  89. horned_worm
  90. hpack
  91. hsluv
  92. httph
  93. index-bench
  94. ip2location
  95. ip2locationio
  96. ip2whois
  97. irmin-graphql
  98. irmin-tezos
  99. jasmin
  100. jhupllib
  101. jose
  102. js_of_ocaml-compiler
  103. jsonschema
  104. jsonschema2atd
  105. jupyter
  106. jupyter-kernel
  107. jwto
  108. kappa-library < "4.1.3"
  109. karamel
  110. kremlin < "transition"
  111. kubecaml
  112. lablgtk3-extras >= "3.0.1"
  113. lambdapi
  114. learn-ocaml
  115. letsencrypt
  116. letters
  117. libsail
  118. linol >= "0.2"
  119. linol-eio
  120. linol-lwt
  121. lockfree >= "0.3.1"
  122. logs-async-reporter >= "1.3"
  123. lsp < "1.6.0"
  124. melange-json = "1.2.0"
  125. melange-json-native
  126. merlin != "4.5-411"
  127. metadb
  128. mirage-crypto-ec
  129. mjson
  130. monorobot
  131. mopsa
  132. morbig >= "0.11.0"
  133. multicore-bench
  134. mutaml
  135. nloge
  136. nsq
  137. obuilder
  138. ocaml-lsp-server < "1.10.5" | >= "1.18.0" & != "1.21.0-4.14" & < "1.23.0"
  139. ocaml-protoc-plugin >= "6.1.0"
  140. ocaml_db_model
  141. ocaml_pgsql_model
  142. ocamleditor >= "1.15.2-ocaml414"
  143. ocsigen-start
  144. odoc >= "3.0.0"
  145. odoc-driver
  146. oframl
  147. oidc
  148. ojs-base
  149. ojs_base
  150. ometrics < "0.2.0"
  151. openai-gym
  152. openapi
  153. openapi_router
  154. openstellina
  155. opium >= "0.19.0"
  156. oraft
  157. orun
  158. osh
  159. ozulip
  160. pa_ppx < "0.14" | >= "0.19"
  161. pandoc
  162. pbrt_yojson
  163. pds-reachability >= "0.2.3"
  164. petr4
  165. phylogenetics >= "0.2.0"
  166. piece_rope
  167. pkcs11-driver >= "1.0.0"
  168. ppx_deriving_jsonschema
  169. ppx_deriving_yojson < "3.6.1"
  170. ppx_protocol_conv_json < "5.0.0" | >= "5.2.1"
  171. ppx_yojson
  172. ppx_yojson_conv < "v0.13.0"
  173. ppx_yojson_conv_lib
  174. prof_spacetime
  175. qmp >= "0.19.0"
  176. quests
  177. r2pipe
  178. radare2
  179. rdf
  180. records = "0.6.0" | >= "1.0.0"
  181. repr-bench
  182. rpclib
  183. rungen
  184. rust-staticlib-gen
  185. SZXX
  186. safemoney
  187. sail < "0.15"
  188. saturn
  189. saturn_lockfree
  190. satyrographos != "0.0.2.7"
  191. savvy
  192. semver2
  193. serde_json
  194. sihl < "0.2.0" | >= "0.3.0~rc2"
  195. sihl-core
  196. slack
  197. slug
  198. smaws-lib
  199. smtml
  200. snf_mcp
  201. spotify-web-api
  202. starred_ml
  203. swagger
  204. tdigest < "2.1.0"
  205. textmate-language >= "0.3.4"
  206. textrazor >= "0.1.1"
  207. tezos-context-hash-irmin
  208. tidy_email_sendgrid
  209. timedesc < "0.8.0"
  210. timedesc-json
  211. timere < "0.4.0"
  212. user-agent-parser
  213. vecosek
  214. vercel
  215. vscoq-language-server
  216. wasm_of_ocaml-compiler
  217. webauthn
  218. why3find
  219. xapi-rrd >= "1.9.0"
  220. yojson-five >= "3.0.0"
  221. yosqlite >= "0.2"
  222. zanuda
  223. zarr

Conflicts

None

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