<img align="right" alt="Ajv logo" width="160" src="https://ajv.js.org/img/ajv.svg">

 

Ajv JSON schema validator

The fastest JSON validator for Node.js and browser.

Supports JSON Schema draft-04/06/07/2019-09/2020-12 (draft-04 support requires ajv-draft-04 package) and JSON Type Definition RFC8927.

Ajv sponsors

<img src="https://ajv.js.org/img/mozilla.svg" width="45%" alt="Mozilla"><img src="https://ajv.js.org/img/gap.svg" width="9%"><img src="https://ajv.js.org/img/reserved.svg" width="45%">

<img src="https://ajv.js.org/img/microsoft.png" width="31%" alt="Microsoft"><img src="https://ajv.js.org/img/gap.svg" width="3%"><img src="https://ajv.js.org/img/reserved.svg" width="31%"><img src="https://ajv.js.org/img/gap.svg" width="3%"><img src="https://ajv.js.org/img/reserved.svg" width="31%">

<img src="https://ajv.js.org/img/retool.svg" width="22.5%" alt="Retool"><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"><img src="https://ajv.js.org/img/gap.svg" width="3%"><img src="https://ajv.js.org/img/simplex.svg" width="22.5%" alt="SimpleX"><img src="https://ajv.js.org/img/gap.svg" width="3%"><img src="https://ajv.js.org/img/reserved.svg" width="22.5%">

Contributing

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.

Please review Contributing guidelines and Code components.

Documentation

All documentation is available on the Ajv website.

Some useful site links:

• Getting started
• JSON Schema vs JSON Type Definition
• API reference
• Strict mode
• Standalone validation code
• Security considerations
• Command line interface
• Frequently Asked Questions

<a name="sponsors"></a>Please sponsor Ajv development

Since I asked to support Ajv development 40 people and 6 organizations contributed via GitHub and OpenCollective - this support helped receiving the MOSS grant!

Your continuing support is very important - the funds will be used to develop and maintain Ajv once the next major version is released.

Please sponsor Ajv via:

• GitHub sponsors page (GitHub will match it)
• Ajv Open Collective

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> <a href="https://opencollective.com/ajv/organization/10/website"><img src="https://opencollective.com/ajv/organization/10/avatar.svg"></a> <a href="https://opencollective.com/ajv/organization/11/website"><img src="https://opencollective.com/ajv/organization/11/avatar.svg"></a> <a href="https://opencollective.com/ajv/organization/12/website"><img src="https://opencollective.com/ajv/organization/12/avatar.svg"></a> <a href="https://opencollective.com/ajv/organization/13/website"><img src="https://opencollective.com/ajv/organization/13/avatar.svg"></a> <a href="https://opencollective.com/ajv/organization/14/website"><img src="https://opencollective.com/ajv/organization/14/avatar.svg"></a> <a href="https://opencollective.com/ajv/organization/15/website"><img src="https://opencollective.com/ajv/organization/15/avatar.svg"></a> <a href="https://opencollective.com/ajv/organization/16/website"><img src="https://opencollective.com/ajv/organization/16/avatar.svg"></a> <a href="https://opencollective.com/ajv/organization/17/website"><img src="https://opencollective.com/ajv/organization/17/avatar.svg"></a> <a href="https://opencollective.com/ajv/organization/18/website"><img src="https://opencollective.com/ajv/organization/18/avatar.svg"></a> <a href="https://opencollective.com/ajv/organization/19/website"><img src="https://opencollective.com/ajv/organization/19/avatar.svg"></a> <a href="https://opencollective.com/ajv/organization/20/website"><img src="https://opencollective.com/ajv/organization/20/avatar.svg"></a> <a href="https://opencollective.com/ajv/organization/21/website"><img src="https://opencollective.com/ajv/organization/21/avatar.svg"></a> <a href="https://opencollective.com/ajv/organization/22/website"><img src="https://opencollective.com/ajv/organization/22/avatar.svg"></a> <a href="https://opencollective.com/ajv/organization/23/website"><img src="https://opencollective.com/ajv/organization/23/avatar.svg"></a> <a href="https://opencollective.com/ajv/organization/24/website"><img src="https://opencollective.com/ajv/organization/24/avatar.svg"></a>

Performance

Ajv generates code 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 - 50% faster than the second place
• jsck benchmark - 20-190% faster
• z-schema benchmark
• themis benchmark

Performance of different validators by json-schema-benchmark:

Features

• Ajv implements JSON Schema draft-06/07/2019-09/2020-12 standards (draft-04 is supported in v6):
  • all validation keywords (see JSON Schema validation keywords)
  • OpenAPI extensions:
    • NEW: keyword discriminator.
    • keyword nullable.
  • full support of remote references (remote schemas have to be added with addSchema or compiled to be available)
  • support of recursive references between schemas
  • correct string lengths for strings with unicode pairs
  • JSON Schema formats (with [ajv-formats](https://github.com/ajv-validator/