Introduction
XGrammar is an open-source engine for structured generation that leverages constrained decoding to guarantee syntactic correctness for outputs such as JSON, regex-constrained text, and custom CFGs.
Key features
- Constraint decoding with near-zero overhead for JSON generation.
- Multi-platform deployment (Linux, macOS, Windows) and multi-language APIs (Python, C++, JS).
- Integrations with inference backends (vLLM, TensorRT-LLM, MLC-LLM), examples, and benchmarks.
Use cases
- Ensure structurally valid JSON or custom-format outputs in production (API responses, data extraction, function-call payloads).
- High-throughput batch generation and low-latency online inference.
- Use as a structured generation backend for inference engines or middleware.
Technical details
- Implemented in C++ with Python bindings; repository includes documentation, examples, and test suites, licensed under Apache-2.0.
- Optimized algorithms for constrained decoding achieve minimal runtime overhead and broad model compatibility.
- Active community and integrations with multiple projects make it suitable for production and research.