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A JSON Schema validation implementation in pure Java, which aims for correctness and performance, in that order

Read me first

The current version of this project is licensed under both LGPLv3 (or later) and ASL 2.0. The old version (2.0.x) was licensed under LGPL 3.0 (or later) only.

Version 2.2 is out. See here for the list of changes compared to 2.0. And of course, it still has all the features of older versions.

What this is

This is an implementation with complete validation support for the latest JSON Schema draft (v4, including hyperschema syntax support) and the previous draft (v3 -- no hyperschema support though). Its list of features would be too long to enumerate here; please refer to the links above!

Should you wonder about it, this library is reported to work on Android. Starting with version 2.2.x, all APK conflicts have been resolved, so you can use this in this context as well.

Google Group

This project has a dedicated Google group. For any questions you have about this software package, feel free to post! The author (me) will try and respond in a timely manner.

Testing online

You can test this library online; this web site is in a project of its own, which you can fork and run by yourself.

Command line

There is a command line application. For this, download the standalone jar (a little more than 5 MiB) from Bintray.

Use java -jar the.jar --help for a detailed list of options.


2.2.x jars are available on Bintray.

Versioning scheme policy

The versioning scheme is defined by the middle digit of the version number:

  • if this number is even, then this is the stable version; no new features will be added to such versions, and the user API will not change (save for some additions if requested).
  • if this number is odd, then this is the development version; new features will be added to those versions only, and the user API may change.

Gradle/Maven artifact


dependencies {
    compile(group: "com.github.fge", name: "json-schema-validator", version: "yourVersionHere");



Relevant documents

This implementation is based on the following drafts:


For a detailed discussion of the implementation, see here.

Please see the wiki for more details.

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