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gpt-oss-120b & gpt-oss-20b Model Card

OpenAI·August 11, 2025

OpenAI

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TL;DR

OpenAI’s first open-weight LLMs since GPT-2: two MoE reasoning models (116.8B and 20.9B) trained largely via distillation, with MXFP4 quantization letting the large model fit a single 80GB GPU. Apache 2.0.

Why it matters

Marked OpenAI’s return to open weights; the 20B model runs on consumer hardware, broadening access to o4-mini-class reasoning.

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