gpt-oss-20b
Weights availableOpen-weight OpenAI model with a 128K-token context window and tool calling. Released August 5, 2025. Weights on Hugging Face.
Access details: OpenAI API
The Hugging Face repository. Download the weights and run them yourself or with a host.
gpt-oss-20bUpdated Sep 23, 2026
Capabilities & limits
- Context window
- 128K
- Maximum output
- 128K
- Image input
- Unsupported
- Tool calling
- Supported
- Structured output
- Supported
Hosted price
Free to download. Running the weights costs whatever your hardware or host charges.
Price history
Sep 23, 2026
Input Not applicable per million tokens
Sep 23, 2026
Output Not applicable per million tokens
Technical details
- Parameters
- 21B
- Active parameters
- 3.6B
- Architecture
- Mixture-of-experts Transformer: 24 layers, 32 experts, 4 active per token
- Training / knowledge cutoff
- Jun 01, 2024
- Input modalities
- Text
- Output modalities
- Text
License
Apache 2.0
From OpenAI
Official announcement ↗Release & lifecycle
- Published
- Aug 5, 2025
- available
- As of Sep 13, 2026