The command-line tool for working with JSON Schema, the world most popular schema language. It is a comprehensive solution for maintaining repositories of schemas and ensuring their quality, both during local development and when running on CI/CD pipelines. For example:

• Ensure your schemas are valid
• Unit test your schemas against valid and invalid instances
• Enforce consistent indentation and keyword ordering in your schema files
• Detect and fix common JSON Schema anti-patterns
• Inline external references for conveniently distributing your schemas

Check out the documentation to learn more

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Tip

Do you want to level up your JSON Schema skills? Check out learnjsonschema.com, our growing JSON Schema documentation website, and our O'Reilly book Unifying Business, Data, and Code: Designing Data Products with JSON Schema.

Version support

We aim to fully support every version of JSON Schema and combinations between them.

Dialect	Support
JSON Schema 2020-12	Full
JSON Schema 2019-09	Full
JSON Schema Draft 7	Full
JSON Schema Draft 6	Full
JSON Schema Draft 4	Full
JSON Schema Draft 3	Partial (except validate, test, and metaschema)
JSON Schema Draft 2	Partial (except validate, test, and metaschema)
JSON Schema Draft 1	Partial (except validate, test, and metaschema)
JSON Schema Draft 0	Partial (except validate, test, and metaschema)

What our users are saying

Amazing product. Very useful for formatting and bundling my schemas, plus it surfaced various referencing issues. 10 out of 10!

@alombarte, co-founder of the KrakenD API Gateway.

Usage

The functionality provided by the JSON Schema CLI is divided into commands. The following pages describe each command in detail. Additionally, running the JSON Schema CLI without passing a command will print convenient reference documentation:

• jsonschema version
• jsonschema validate
• jsonschema metaschema (ensure a schema is valid)
• jsonschema test (write unit tests for your schemas)
• jsonschema fmt
• jsonschema lint
• jsonschema bundle (for inlining remote references in a schema)
• jsonschema inspect (for debugging references)
• jsonschema encode (for binary compression)
• jsonschema decode

Note that YAML is supported in most commands!

We also support a growing amount of pre-commit hooks. Take a look at the .pre-commit-hooks.yaml configuration file for what's available right now. Keep in mind that to use the pre-commit hooks, you need to install the CLI first.

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If you are looking for more of a tutorial and overview of what the CLI is capable of, take a look at the Applying software engineering practices to JSON Schemas talk from the 2024 JSON Schema Conference. It covers advise on ontology design, linting, unit testing, CI/CD integration, and more:

Installation

The JSON Schema CLI is written using C++ and CMake, and supports macOS, Windows, and GNU/Linux.

From Homebrew

brew install sourcemeta/apps/jsonschema

From GitHub Actions

- uses: sourcemeta/jsonschema@vX.Y.Z

Where X.Y.Z is replaced with the desired version. For example:

- uses: sourcemeta/jsonschema@v8.1.0
# Then use as usual
- run: jsonschema fmt path/to/schemas --check

From NPM

npm install --global @sourcemeta/jsonschema

From GitHub Releases

We publish precompiled binaries for every supported platform to GitHub Releases, including a continuous that is updated on every commit from the main branch.

For convenience, we also provide a POSIX shell script capable of installing the latest pre-built binaries, which you can run as follows:

/bin/sh -c "$(curl -fsSL https://raw.githubusercontent.com/sourcemeta/jsonschema/main/install -H "Cache-Control: no-cache, no-store, must-revalidate")"

From Dockerfile

Starting from v7.2.1, we publish a Docker image to GitHub Packages (amd64 and arm64), which you can use as follows:

docker run --interactive --volume "$PWD:/workspace" \
  ghcr.io/sourcemeta/jsonschema:vX.Y.Z lint --verbose myschema.json

Replace vX.Y.Z with your desired version. You can mount any directory as /workspace.

Warning

Make sure to NOT allocate a pseudo-TTY when running the CLI through Docker (i.e. the --tty/-t option) as it might result in line ending incompatibilities between the container and host, which will affect formatting. Plus a TTY is not required for running a tool like the JSON Schema CLI.

Building from source

git clone https://github.com/sourcemeta/jsonschema
cd jsonschema
cmake -S . -B ./build -DCMAKE_BUILD_TYPE:STRING=Release
cmake --build ./build --config Release --parallel 4
cmake --install ./build --prefix <prefix> \
  --config Release --verbose --component sourcemeta_jsonschema

Where <prefix> can be any destination prefix of your choosing, such as /opt or /usr/local.