Suggestions appear as you type. Use the up and down arrows to choose one and Enter to open it.

This page's audience our own tag's counts — open to see them
–Visits
–Page views
–Clicks to vendors
–Time on page
–Reading now
Clicks to vendors, by tool
  • –
Top countries
  • –
Devices
  • –

– · visits, page views and clicks counted by our own tag, which counts more than our checked analytics; every figure rounded down · how we count

Ajv review

Free#18 of 29 in JSON Tools

A highly capable validator for JavaScript teams that need deep schema support.

7.4/10Editor score
Visit Ajv
Ajv7.4 Visit Ajv

Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026

Ajv is an open-source JavaScript library for validating JSON data against JSON Schema and JSON Type Definition schemas. It is intended for developers working with API payloads, configuration files, and other JavaScript data across browser, Node.js, and command-line workflows. The library supports web-based JavaScript applications and offers a free plan under its open-source pricing model.

Schema coverage is the standout strength. Ajv supports JSON Schema drafts 04, 06, 07, 2019-09, and 2020-12, along with JSON Type Definition. It can compile schemas into JavaScript validation functions and generate standalone validation code. Referenced and recursive schemas support more involved data models, while custom keywords and formats extend validation rules. Asynchronous validation is available for user-defined formats and keywords, and JTD schemas can produce compiled JSON parsers and serializers. These capabilities make Ajv a strong fit when validation depth and generated JavaScript code matter more than a minimal API.

Ajv also covers operational workflows through command-line validation of multiple data files, although that workflow uses the separate ajv-cli package. Its open-source model suits teams that want a library they can incorporate into JavaScript applications without a paid-plan structure. The trade-off is focus: Ajv is specialized around JSON validation and JavaScript, so a simpler validator may be a better choice for basic schemas or teams seeking a narrower set of configuration options. Choose Ajv when draft coverage, schema references, custom rules, asynchronous checks, or compiled output are central requirements.

Ajv pros and cons

  • Where it wins
    • Supports JSON Schema drafts 04, 06, 07, 2019-09, and 2020-12
    • Compiles schemas into JavaScript validators and standalone code
    • Adds recursive schemas, custom keywords, async validation, and JTD parsers
  • Where it doesn't
    • Focused on JavaScript applications rather than a general-purpose tool
    • Command-line workflows require the separate ajv-cli package
    • Its extensive schema options may exceed simpler validation needs

Ajv fact sheet, pricing and score →

Advertiser disclosure: iTechGuides is reader-supported. Vendors can pay for top positions in our rankings and for a place on other products' pages, and we may earn a commission when you click some links. Bought places stand at the number bought; this page and our disclosure say so. Paying vendors may get a fuller, more detailed review from our editors, and that review can change their score. How we rank.

Last updated · How we research and update