XGrammar

What ChatGPT, Claude, Gemini & Grok actually say · July 2026

The verdict

XGrammar appears in 1 AI-ranked category.

#7🧱 Best structured output tool for LLMs2/4 models · updated 2026-07-12

GPT —Claude —Gemini #5Grok #5

Extremely high-performance grammar compilation and token masking engine built for production-scale inference runtimes like vLLM, SGLang, and MLC-LLM

Grok Default high-performance constrained engine in vLLM/SGLang/TensorRT-LLM for self-hosted LLMs, fast token-level guarantees, broad schema support, and production-grade throughput without external dependencies.

What would move XGrammar up

Gemini Simplify its low-level integration API and documentation to make it easier for general application developers to adopt
Grok Improve documentation and ease of schema definition for non-expert users compared to higher-level libraries

Top alternatives per the models: Instructor · BAML · Outlines · OpenAI Structured Outputs

Rankings are computed from what the models answer, re-polled continuously · raw reasoning shown verbatim · methodology