gpt-oss-120b

gpt-oss-120b is an open-weight, 117B-parameter Mixture-of-Experts (MoE) language model from OpenAI designed for high-reasoning, agentic, and general-purpose production use cases. It activates 5.1B parameters per forward pass and is optimized to run on a single H100 GPU with native MXFP4 quantization. The model supports configurable reasoning depth, full chain-of-thought access, and native tool use, including function calling, browsing, and structured output generation.

ChatOpenAI131k tokens$0.0327 / $0.1853 · 1M

openai/gpt-oss-120b

Context
131k tokens
Completion cap
131,072
Tools
Yes
JSON
Yes
Released
2025-08-05

Call it from Geek Hub

Same OpenAI SDK. Change the base URL and the model id.

curl https://api.geekhub.mx/v1/chat/completions \
  -H "Authorization: Bearer $GEEKHUB_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-oss-120b",
    "messages": [{"role": "user", "content": "Hola"}]
  }'
Get an API key

Frequently asked questions

What is gpt-oss-120b?
gpt-oss-120b is an open-weight, 117B-parameter Mixture-of-Experts (MoE) language model from OpenAI designed for high-reasoning, agentic, and general-purpose production use cases. It activates 5.1B parameters per forward pass and is optimized to run on a single H100 GPU with native MXFP4 quantization. The model supports configurable reasoning depth, full chain-of-thought access, and native tool use, including function calling, browsing, and structured output generation. gpt-oss-120b runs on the Geek Hub API (OpenAI-compatible). Model id: openai/gpt-oss-120b.
Is gpt-oss-120b free?
No. Input is $0.0327 per 1M tokens and output is $0.1853 per 1M tokens on Geek Hub (markup included).
What is the context length of gpt-oss-120b?
gpt-oss-120b has a 131k tokens context window. It supports up to 131,072 completion tokens.
Does gpt-oss-120b support tool calling and structured outputs?
gpt-oss-120b accepts tools and tool_choice for function calling. It also supports structured outputs via a JSON schema in response_format.
When was gpt-oss-120b released?
gpt-oss-120b was released on 2025-08-05.

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