1 <img align="right" alt="Ajv logo" width="160" src="https://ajv.js.org/img/ajv.svg">
5 # Ajv JSON schema validator
7 The fastest JSON validator for Node.js and browser.
9 Supports JSON Schema draft-04/06/07/2019-09/2020-12 ([draft-04 support](https://ajv.js.org/json-schema.html#draft-04) requires ajv-draft-04 package) and JSON Type Definition [RFC8927](https://datatracker.ietf.org/doc/rfc8927/).
11 [![build](https://github.com/ajv-validator/ajv/workflows/build/badge.svg)](https://github.com/ajv-validator/ajv/actions?query=workflow%3Abuild)
12 [![npm](https://img.shields.io/npm/v/ajv.svg)](https://www.npmjs.com/package/ajv)
13 [![npm downloads](https://img.shields.io/npm/dm/ajv.svg)](https://www.npmjs.com/package/ajv)
14 [![Coverage Status](https://coveralls.io/repos/github/ajv-validator/ajv/badge.svg?branch=master)](https://coveralls.io/github/ajv-validator/ajv?branch=master)
15 [![Gitter](https://img.shields.io/gitter/room/ajv-validator/ajv.svg)](https://gitter.im/ajv-validator/ajv)
16 [![GitHub Sponsors](https://img.shields.io/badge/$-sponsors-brightgreen)](https://github.com/sponsors/epoberezkin)
20 [<img src="https://ajv.js.org/img/mozilla.svg" width="45%" alt="Mozilla">](https://www.mozilla.org)<img src="https://ajv.js.org/img/gap.svg" width="9%">[<img src="https://ajv.js.org/img/reserved.svg" width="45%">](https://opencollective.com/ajv)
22 [<img src="https://ajv.js.org/img/microsoft.png" width="31%" alt="Microsoft">](https://opensource.microsoft.com)<img src="https://ajv.js.org/img/gap.svg" width="3%">[<img src="https://ajv.js.org/img/reserved.svg" width="31%">](https://opencollective.com/ajv)<img src="https://ajv.js.org/img/gap.svg" width="3%">[<img src="https://ajv.js.org/img/reserved.svg" width="31%">](https://opencollective.com/ajv)
24 [<img src="https://ajv.js.org/img/retool.svg" width="22.5%" alt="Retool">](https://retool.com/?utm_source=sponsor&utm_campaign=ajv)<img src="https://ajv.js.org/img/gap.svg" width="3%">[<img src="https://ajv.js.org/img/tidelift.svg" width="22.5%" alt="Tidelift">](https://tidelift.com/subscription/pkg/npm-ajv?utm_source=npm-ajv&utm_medium=referral&utm_campaign=enterprise)<img src="https://ajv.js.org/img/gap.svg" width="3%">[<img src="https://ajv.js.org/img/reserved.svg" width="22.5%">](https://opencollective.com/ajv)<img src="https://ajv.js.org/img/gap.svg" width="3%">[<img src="https://ajv.js.org/img/reserved.svg" width="22.5%">](https://opencollective.com/ajv)
28 More than 100 people contributed to Ajv, and we would love to have you join the development. We welcome implementing new features that will benefit many users and ideas to improve our documentation.
30 Please review [Contributing guidelines](./CONTRIBUTING.md) and [Code components](https://ajv.js.org/components.html).
34 All documentation is available on the [Ajv website](https://ajv.js.org).
36 Some useful site links:
37 - [Getting started](https://ajv.js.org/guide/getting-started.html)
38 - [JSON Schema vs JSON Type Definition](https://ajv.js.org/guide/schema-language.html)
39 - [API reference](https://ajv.js.org/api.html)
40 - [Strict mode](https://ajv.js.org/strict-mode.html)
41 - [Standalone validation code](https://ajv.js.org/standalone.html)
42 - [Security considerations](https://ajv.js.org/security.html)
43 - [Command line interface](https://ajv.js.org/packages/ajv-cli.html)
44 - [Frequently Asked Questions](https://ajv.js.org/faq.html)
46 ## <a name="sponsors"></a>Please [sponsor Ajv development](https://github.com/sponsors/epoberezkin)
48 Since I asked to support Ajv development 40 people and 6 organizations contributed via GitHub and OpenCollective - this support helped receiving the MOSS grant!
50 Your continuing support is very important - the funds will be used to develop and maintain Ajv once the next major version is released.
52 Please sponsor Ajv via:
54 - [GitHub sponsors page](https://github.com/sponsors/epoberezkin) (GitHub will match it)
55 - [Ajv Open Collective️](https://opencollective.com/ajv)
59 #### Open Collective sponsors
61 <a href="https://opencollective.com/ajv"><img src="https://opencollective.com/ajv/individuals.svg?width=890"></a>
63 <a href="https://opencollective.com/ajv/organization/0/website"><img src="https://opencollective.com/ajv/organization/0/avatar.svg"></a>
64 <a href="https://opencollective.com/ajv/organization/1/website"><img src="https://opencollective.com/ajv/organization/1/avatar.svg"></a>
65 <a href="https://opencollective.com/ajv/organization/2/website"><img src="https://opencollective.com/ajv/organization/2/avatar.svg"></a>
66 <a href="https://opencollective.com/ajv/organization/3/website"><img src="https://opencollective.com/ajv/organization/3/avatar.svg"></a>
67 <a href="https://opencollective.com/ajv/organization/4/website"><img src="https://opencollective.com/ajv/organization/4/avatar.svg"></a>
68 <a href="https://opencollective.com/ajv/organization/5/website"><img src="https://opencollective.com/ajv/organization/5/avatar.svg"></a>
69 <a href="https://opencollective.com/ajv/organization/6/website"><img src="https://opencollective.com/ajv/organization/6/avatar.svg"></a>
70 <a href="https://opencollective.com/ajv/organization/7/website"><img src="https://opencollective.com/ajv/organization/7/avatar.svg"></a>
71 <a href="https://opencollective.com/ajv/organization/8/website"><img src="https://opencollective.com/ajv/organization/8/avatar.svg"></a>
72 <a href="https://opencollective.com/ajv/organization/9/website"><img src="https://opencollective.com/ajv/organization/9/avatar.svg"></a>
73 <a href="https://opencollective.com/ajv/organization/10/website"><img src="https://opencollective.com/ajv/organization/10/avatar.svg"></a>
74 <a href="https://opencollective.com/ajv/organization/11/website"><img src="https://opencollective.com/ajv/organization/11/avatar.svg"></a>
78 Ajv generates code to turn JSON Schemas into super-fast validation functions that are efficient for v8 optimization.
80 Currently Ajv is the fastest and the most standard compliant validator according to these benchmarks:
82 - [json-schema-benchmark](https://github.com/ebdrup/json-schema-benchmark) - 50% faster than the second place
83 - [jsck benchmark](https://github.com/pandastrike/jsck#benchmarks) - 20-190% faster
84 - [z-schema benchmark](https://rawgit.com/zaggino/z-schema/master/benchmark/results.html)
85 - [themis benchmark](https://cdn.rawgit.com/playlyfe/themis/master/benchmark/results.html)
87 Performance of different validators by [json-schema-benchmark](https://github.com/ebdrup/json-schema-benchmark):
89 [![performance](https://chart.googleapis.com/chart?chxt=x,y&cht=bhs&chco=76A4FB&chls=2.0&chbh=62,4,1&chs=600x416&chxl=-1:|ajv|@exodus/schemasafe|is-my-json-valid|djv|@cfworker/json-schema|jsonschema&chd=t:100,69.2,51.5,13.1,5.1,1.2)](https://github.com/ebdrup/json-schema-benchmark/blob/master/README.md#performance)
93 - Ajv implements JSON Schema [draft-06/07/2019-09/2020-12](http://json-schema.org/) standards (draft-04 is supported in v6):
94 - all validation keywords (see [JSON Schema validation keywords](https://ajv.js.org/json-schema.html))
95 - [OpenAPI](https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.3.md) extensions:
96 - NEW: keyword [discriminator](https://ajv.js.org/json-schema.html#discriminator).
97 - keyword [nullable](https://ajv.js.org/json-schema.html#nullable).
98 - full support of remote references (remote schemas have to be added with `addSchema` or compiled to be available)
99 - support of recursive references between schemas
100 - correct string lengths for strings with unicode pairs
101 - JSON Schema [formats](https://ajv.js.org/guide/formats.html) (with [ajv-formats](https://github.com/ajv-validator/ajv-formats) plugin).
102 - [validates schemas against meta-schema](https://ajv.js.org/api.html#api-validateschema)
103 - NEW: supports [JSON Type Definition](https://datatracker.ietf.org/doc/rfc8927/):
104 - all keywords (see [JSON Type Definition schema forms](https://ajv.js.org/json-type-definition.html))
105 - meta-schema for JTD schemas
106 - "union" keyword and user-defined keywords (can be used inside "metadata" member of the schema)
107 - supports [browsers](https://ajv.js.org/guide/environments.html#browsers) and Node.js 10.x - current
108 - [asynchronous loading](https://ajv.js.org/guide/managing-schemas.html#asynchronous-schema-loading) of referenced schemas during compilation
109 - "All errors" validation mode with [option allErrors](https://ajv.js.org/options.html#allerrors)
110 - [error messages with parameters](https://ajv.js.org/api.html#validation-errors) describing error reasons to allow error message generation
111 - i18n error messages support with [ajv-i18n](https://github.com/ajv-validator/ajv-i18n) package
112 - [removing-additional-properties](https://ajv.js.org/guide/modifying-data.html#removing-additional-properties)
113 - [assigning defaults](https://ajv.js.org/guide/modifying-data.html#assigning-defaults) to missing properties and items
114 - [coercing data](https://ajv.js.org/guide/modifying-data.html#coercing-data-types) to the types specified in `type` keywords
115 - [user-defined keywords](https://ajv.js.org/guide/user-keywords.html)
116 - additional extension keywords with [ajv-keywords](https://github.com/ajv-validator/ajv-keywords) package
117 - [\$data reference](https://ajv.js.org/guide/combining-schemas.html#data-reference) to use values from the validated data as values for the schema keywords
118 - [asynchronous validation](https://ajv.js.org/guide/async-validation.html) of user-defined formats and keywords
122 To install version 8:
128 ## <a name="usage"></a>Getting started
130 Try it in the Node.js REPL: https://runkit.com/npm/ajv
135 // or ESM/TypeScript import
136 import Ajv from "ajv"
138 const Ajv = require("ajv")
140 const ajv = new Ajv() // options can be passed, e.g. {allErrors: true}
145 foo: {type: "integer"},
146 bar: {type: "string"}
149 additionalProperties: false,
157 const validate = ajv.compile(schema)
158 const valid = validate(data)
159 if (!valid) console.log(validate.errors)
162 Learn how to use Ajv and see more examples in the [Guide: getting started](https://ajv.js.org/guide/getting-started.html)
166 See [https://github.com/ajv-validator/ajv/releases](https://github.com/ajv-validator/ajv/releases)
168 **Please note**: [Changes in version 8.0.0](https://github.com/ajv-validator/ajv/releases/tag/v8.0.0)
170 [Version 7.0.0](https://github.com/ajv-validator/ajv/releases/tag/v7.0.0)
172 [Version 6.0.0](https://github.com/ajv-validator/ajv/releases/tag/v6.0.0).
176 Please review and follow the [Code of conduct](./CODE_OF_CONDUCT.md).
178 Please report any unacceptable behaviour to ajv.validator@gmail.com - it will be reviewed by the project team.
182 To report a security vulnerability, please use the
183 [Tidelift security contact](https://tidelift.com/security).
184 Tidelift will coordinate the fix and disclosure. Please do NOT report security vulnerabilities via GitHub issues.
186 ## Open-source software support
188 Ajv is a part of [Tidelift subscription](https://tidelift.com/subscription/pkg/npm-ajv?utm_source=npm-ajv&utm_medium=referral&utm_campaign=readme) - it provides a centralised support to open-source software users, in addition to the support provided by software maintainers.