Blaze ===== The ultra high-performance JSON Schema validator for C++ with support for JSON Schema Draft 4, Draft 6, Draft 7, 2019-09, and 2020-12. [![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.14867298.svg)](https://doi.org/10.5281/zenodo.14867298) ![Supported Dialects](https://img.shields.io/endpoint?url=https%3A%2F%2Fbowtie.report%2Fbadges%2Fc%2B%2B-blaze%2Fsupported_versions.json) ![Draft 2020-12](https://img.shields.io/endpoint?url=https%3A%2F%2Fbowtie.report%2Fbadges%2Fc%2B%2B-blaze%2Fcompliance%2Fdraft2020-12.json) ![Draft 2019-09](https://img.shields.io/endpoint?url=https%3A%2F%2Fbowtie.report%2Fbadges%2Fc%2B%2B-blaze%2Fcompliance%2Fdraft2019-09.json) ![Draft 7](https://img.shields.io/endpoint?url=https%3A%2F%2Fbowtie.report%2Fbadges%2Fc%2B%2B-blaze%2Fcompliance%2Fdraft7.json) ![Draft 6](https://img.shields.io/endpoint?url=https%3A%2F%2Fbowtie.report%2Fbadges%2Fc%2B%2B-blaze%2Fcompliance%2Fdraft6.json) ![Draft 4](https://img.shields.io/endpoint?url=https%3A%2F%2Fbowtie.report%2Fbadges%2Fc%2B%2B-blaze%2Fcompliance%2Fdraft4.json) Want to use Blaze without writing C++? Check out our [JSON Schema CLI](https://github.com/sourcemeta/jsonschema), which is powered by Blaze, and offers advanced functionality like [`validate --trace`](https://github.com/sourcemeta/jsonschema/blob/main/docs/validate.markdown) for debugging schema evaluation. Benchmark --------- The 2025 paper [Blaze: Compiling JSON Schema for 10x Faster Validation](https://arxiv.org/abs/2503.02770) presents a reproducible benchmark comparing Blaze against a number of popular JSON Schema validators, concluding that Blaze is on average _at least_ 10x faster than competitors given a large set of representative schemas and instances. [![](./assets/banner.png)](https://arxiv.org/abs/2503.02770) Features -------- - **Performance:** Blaze compiles JSON Schema into a lower-level intermediate language for ultra fast evaluation. It can achieve schema validation in the nano-second range, making it a perfect fit for low-latency gateways and validation of large datasets - **Compliance:** Blaze achieves a 100% compliance score in the official [Bowtie](https://bowtie.report/#/implementations/cpp-blaze) benchmark, while popular validators like [AJV](https://bowtie.report/#/implementations/js-ajv) only achieve an average 85% compliance. It also supports the [Standard Output](https://json-schema.org/draft/2020-12/json-schema-core#name-output-formatting) format (Flag, and Basic). Furthermore, Blaze is built and maintained by a [JSON Schema TSC member](https://www.jviotti.com) - **Extensibility:** Blaze supports the implementation of custom vocabularies of arbitrary complexity, and the ability to setup custom resolution of external schemas from arbitrary sources, like from HTTP, filesystem, databases, etc - **Annotations:** Blaze is one of the few implementations that fully supports annotation extraction during evaluation to augment instances with semantic information, making it a great fit for data science scenarios Blaze also adheres to the [annotations official test suite](https://github.com/json-schema-org/JSON-Schema-Test-Suite/tree/main/annotations) Example ------- Blaze is designed to be easy to use, while at the same time providing extensive hooks for supporting custom vocabularies, resolving external schemas, and more. ```cpp // (1) Get a JSON Schema const auto schema{sourcemeta::core::parse(R"JSON({ "$schema": "https://json-schema.org/draft/2020-12/schema", "type": "string" })JSON")}; // (2) Compile the JSON Schema into an optimised representation const auto compiled_schema{sourcemeta::blaze::compile( schema, // These options allow you tweak how Blaze works, // the JSON Schema vocabularies it understands, // and how to resolve references to external schemas sourcemeta::core::schema_official_walker, sourcemeta::core::schema_official_resolver, sourcemeta::blaze::default_schema_compiler, // Fast validation means getting to a boolean result // as fast as possible. Check out the documentation // for how to get detailed error information and/or // collect JSON Schema annotations sourcemeta::blaze::Mode::FastValidation)}; // (3) Get a JSON instance const sourcemeta::core::JSON instance{"Hello Blaze!"}; // (4) Validate the instance against the schema sourcemeta::blaze::Evaluator evaluator; const auto result{evaluator.validate(compiled_schema, instance)}; if (result) { std::cout << "Success!\n"; } ``` Documentation ------------- Refer to the project website for documentation: [https://blaze.sourcemeta.com](https://blaze.sourcemeta.com). Roadmap ------- - Support running the validator on [simdjson](https://github.com/simdjson/simdjson) - Provide bindings to higher-level programming languages (Node.js, Go, etc) Contributors ------------ Blaze was designed and developed by a team of passionate JSON Schema developers and researchers.