OpenAI releases gpt-oss, its first open-weight LLMs since GPT-2
Confirmed
The takeaway
OpenAI released gpt-oss-120b and gpt-oss-20b, open-weight reasoning models under Apache 2.0; the larger one approached o4-mini on core reasoning benchmarks and ran on a single 80GB GPU.
Status
- Claim
Confirmed
- Our reporting
- High confidence
- Importance
- 3 of 5
- Last verified
- 29 September 2026
Your AI and this story
- GPT-6 AstraIn its training data
- Claude Opus 5.5In its training data
- Gemini 4 HydrogenIn its training data
- Grok 4.7In its training data
It happened before the cutoffs of all four assistants, so it can be in their training data.
Key facts
- Released 5 August 2025
- gpt-oss-120b and gpt-oss-20b, mixture-of-experts
- Apache 2.0 license
- 120b runs on a single 80GB GPU (near-parity with o4-mini on core reasoning, per OpenAI); 20b on devices with 16GB memory
- Active parameters per token: 5.1B (120b) and 3.6B (20b)
- First OpenAI open-weight language models since GPT-2 (2019)
What happened
OpenAI returned to releasing open weights, partly in response to the rise of Chinese open models.
Why it matters
Gave the US a competitive open-weight reasoning model and ended OpenAI’s six-year hiatus from open releases.
Sources
2 sources from 2 sites. Numbers match the chips in the text.
2 sources: 2 primary
Primary
- Introducing gpt-oss (OpenAI)openai.com, official
- openai/gpt-oss (code)github.com, code
Changes
- Filed