openai/harmony

Health v2 · maintenance only

Flags: no_releases

Adoption not part of the score

4487 stars · 302 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-29, confidence not recorded

OpenAI's Rust library (with first-class Python bindings) for rendering and parsing the harmony response format used by its open-weight gpt-oss models. It handles conversation structure, reasoning channels, and tool-call formatting so custom inference stacks can produce loss-free prompt sequences.

Use cases

• build a custom inference server for gpt-oss models
• render harmony-format prompts for local LLM inference
• parse model output channels like analysis, commentary, and final
• format tool calls and structured outputs for gpt-oss
• implement gpt-oss support in vLLM or Ollama-like runtimes
• convert chat messages into the harmony token format

When to choose

• you are building your own inference engine or runtime for gpt-oss
• you need loss-free rendering and parsing of the harmony format
• you want a fast Rust implementation with typed Python bindings

When to avoid

• you access gpt-oss through an API or provider like HuggingFace, Ollama, or vLLM that already handles formatting
• you work with models that do not use the harmony response format

Facets

library · maturity active

llm-inference serialization parser sdk large-language-models developer-tools rust python cross-platform gpt-oss prompt-format tokenizer-format openai chat-template tool-calling natural-language-processing

Member repositories

For agents

markdown · JSON · MCP: product_card(name="openai/harmony")