<img align="right" alt="Ajv logo" width="160" src="https://ajv.js.org/images/ajv_logo.png">
# Ajv: Another JSON Schema Validator
The fastest JSON Schema validator for Node.js and browser. Supports draft-04/06/07.
[![Build Status](https://travis-ci.org/ajv-validator/ajv.svg?branch=master)](https://travis-ci.org/ajv-validator/ajv)
[![npm](https://img.shields.io/npm/v/ajv.svg)](https://www.npmjs.com/package/ajv)
[![npm downloads](https://img.shields.io/npm/dm/ajv.svg)](https://www.npmjs.com/package/ajv)
[![Coverage Status](https://coveralls.io/repos/github/ajv-validator/ajv/badge.svg?branch=master)](https://coveralls.io/github/ajv-validator/ajv?branch=master)
[![Gitter](https://img.shields.io/gitter/room/ajv-validator/ajv.svg)](https://gitter.im/ajv-validator/ajv)
[![GitHub Sponsors](https://img.shields.io/badge/$-sponsors-brightgreen)](https://github.com/sponsors/epoberezkin)
## Please [sponsor Ajv development](https://github.com/sponsors/epoberezkin)
I will get straight to the point - I need your support to ensure that the development of Ajv continues.
I have developed Ajv for 5 years in my free time, but it is not sustainable. I'd appreciate if you consider supporting its further development with donations:
- [GitHub sponsors page](https://github.com/sponsors/epoberezkin) (GitHub will match it)
- [Ajv Open Collectiveï¸](https://opencollective.com/ajv)
There are many small and large improvements that are long due, including the support of the next versions of JSON Schema specification, improving website and documentation, and making Ajv more modular and maintainable to address its limitations - what Ajv needs to evolve is much more than what I can contribute in my free time.
I would also really appreciate any advice you could give on how to raise funds for Ajv development - whether some suitable open-source fund I could apply to or some sponsor I should approach.
Since 2015 Ajv has become widely used, thanks to your help and contributions:
- **90** contributors ð
- **5,000** dependent npm packages âï¸
- **7,000** github stars, from GitHub users [all over the world](https://www.google.com/maps/d/u/0/viewer?mid=1MGRV8ciFUGIbO1l0EKFWNJGYE7iSkDxP&ll=-3.81666561775622e-14%2C4.821737100000007&z=2) âï¸
- **5,000,000** dependent repositories on GitHub ð
- **120,000,000** npm downloads per month! ð¯
I believe it would benefit all Ajv users to help put together the fund that will be used for its further development - it would allow to bring some additional maintainers to the project.
Thank you
#### Open Collective sponsors
<a href="https://opencollective.com/ajv"><img src="https://opencollective.com/ajv/individuals.svg?width=890"></a>
<a href="https://opencollective.com/ajv/organization/0/website"><img src="https://opencollective.com/ajv/organization/0/avatar.svg"></a>
<a href="https://opencollective.com/ajv/organization/1/website"><img src="https://opencollective.com/ajv/organization/1/avatar.svg"></a>
<a href="https://opencollective.com/ajv/organization/2/website"><img src="https://opencollective.com/ajv/organization/2/avatar.svg"></a>
<a href="https://opencollective.com/ajv/organization/3/website"><img src="https://opencollective.com/ajv/organization/3/avatar.svg"></a>
<a href="https://opencollective.com/ajv/organization/4/website"><img src="https://opencollective.com/ajv/organization/4/avatar.svg"></a>
<a href="https://opencollective.com/ajv/organization/5/website"><img src="https://opencollective.com/ajv/organization/5/avatar.svg"></a>
<a href="https://opencollective.com/ajv/organization/6/website"><img src="https://opencollective.com/ajv/organization/6/avatar.svg"></a>
<a href="https://opencollective.com/ajv/organization/7/website"><img src="https://opencollective.com/ajv/organization/7/avatar.svg"></a>
<a href="https://opencollective.com/ajv/organization/8/website"><img src="https://opencollective.com/ajv/organization/8/avatar.svg"></a>
<a href="https://opencollective.com/ajv/organization/9/website"><img src="https://opencollective.com/ajv/organization/9/avatar.svg"></a>
## Using version 6
[JSON Schema draft-07](http://json-schema.org/latest/json-schema-validation.html) is published.
[Ajv version 6.0.0](https://github.com/ajv-validator/ajv/releases/tag/v6.0.0) that supports draft-07 is released. It may require either migrating your schemas or updating your code (to continue using draft-04 and v5 schemas, draft-06 schemas will be supported without changes).
__Please note__: To use Ajv with draft-06 schemas you need to explicitly add the meta-schema to the validator instance:
```javascript
ajv.addMetaSchema(require('ajv/lib/refs/json-schema-draft-06.json'));
```
To use Ajv with draft-04 schemas in addition to explicitly adding meta-schema you also need to use option schemaId:
```javascript
var ajv = new Ajv({schemaId: 'id'});
// If you want to use both draft-04 and draft-06/07 schemas:
// var ajv = new Ajv({schemaId: 'auto'});
ajv.addMetaSchema(require('ajv/lib/refs/json-schema-draft-04.json'));
```
## Contents
- [Performance](#performance)
- [Features](#features)
- [Getting started](#getting-started)
- [Frequently Asked Questions](https://github.com/ajv-validator/ajv/blob/master/FAQ.md)
- [Using in browser](#using-in-browser)
- [Ajv and Content Security Policies (CSP)](#ajv-and-content-security-policies-csp)
- [Command line interface](#command-line-interface)
- Validation
- [Keywords](#validation-keywords)
- [Annotation keywords](#annotation-keywords)
- [Formats](#formats)
- [Combining schemas with $ref](#ref)
- [$data reference](#data-reference)
- NEW: [$merge and $patch keywords](#merge-and-patch-keywords)
- [Defining custom keywords](#defining-custom-keywords)
- [Asynchronous schema compilation](#asynchronous-schema-compilation)
- [Asynchronous validation](#asynchronous-validation)
- [Security considerations](#security-considerations)
- [Security contact](#security-contact)
- [Untrusted schemas](#untrusted-schemas)
- [Circular references in objects](#circular-references-in-javascript-objects)
- [Trusted schemas](#security-risks-of-trusted-schemas)
- [ReDoS attack](#redos-attack)
- Modifying data during validation
- [Filtering data](#filtering-data)
- [Assigning defaults](#assigning-defaults)
- [Coercing data types](#coercing-data-types)
- API
- [Methods](#api)
- [Options](#options)
- [Validation errors](#validation-errors)
- [Plugins](#plugins)
- [Related packages](#related-packages)
- [Some packages using Ajv](#some-packages-using-ajv)
- [Tests, Contributing, Changes history](#tests)
- [Support, Code of conduct, License](#open-source-software-support)
## Performance
Ajv generates code using [doT templates](https://github.com/olado/doT) to turn JSON Schemas into super-fast validation functions that are efficient for v8 optimization.
Currently Ajv is the fastest and the most standard compliant validator according to these benchmarks:
- [json-schema-benchmark](https://github.com/ebdrup/json-schema-benchmark) - 50% faster than the second place
- [jsck benchmark](https://github.com/pandastrike/jsck#benchmarks) - 20-190% faster
- [z-schema benchmark](https://rawgit.com/zaggino/z-schema/master/benchmark/results.html)
- [themis benchmark](https://cdn.rawgit.com/playlyfe/themis/master/benchmark/results.html)
Performance of different validators by [json-schema-benchmark](https://github.com/ebdrup/json-schema-benchmark):
[![performance](https://chart.googleapis.com/chart?chxt=x,y&cht=bhs&chco=76A4FB&chls=2.0&chbh=32,4,1&chs=600x416&chxl=-1:|djv|ajv|json-schema-validator-generator|jsen|is-my-json-valid|themis|z-schema|jsck|skeemas|json-schema-library|tv4&chd=t:100,98,72.1,66.8,50.1,15.1,6.1,3.8,1.2,0.7,0.2)](https://github.com/ebdrup/json-schema-benchmark/blob/master/README.md#performance)
## Features
- Ajv implements full JSON Schema [draft-06/07](http://json-schema.org/) and draft-04 standards:
- all validation keywords (see [JSON Schema validation keywords](http
评论1