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

Conflicts

None

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