Model page
GPT OSS 20b
OpenAI's open-weight 21B MoE via Fireworks. Lower latency, local or specialized use-cases. 131k context. Does not support web search, image input, or function calling.
Key dates
We use concrete dates and keep them consistent across the site.
Capability
Context window
131,072 tokens
Capability
Max output
20,000 tokens
ChatGPT
GPT‑4o retirement (ChatGPT)
OpenAI is retiring GPT‑4o inside ChatGPT on February 13, 2026. This does not automatically imply API removal.