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gpt-oss-20b (free)
gpt-oss-20b is an open-weight 21B parameter model released by OpenAI under the Apache 2.0 license. It uses a Mixture-of-Experts (MoE) architecture with 3.6B active parameters per forward pass, optimized for lower-latency inference and deployability on consumer or single-GPU hardware. The model is trained in OpenAI’s Harmony response format and supports reasoning level configuration, fine-tuning, and agentic capabilities including function calling, tool use, and structured outputs.
8/5/2025
131,072 tokens
Specifications
Modalities
Input
text
Output
text
Supported Parameters
include_reasoning
max_tokens
reasoning
seed
stop
temperature
tool_choice
tools
Max Output Tokens
131,072Data policy
- Prompt retention
- Unknown — we could not confirm
- Training
- Unknown — not declared
"Unknown" does not mean "safe". It means we could not confirm it.
Whether a provider trains on prompts is a declared value from our terms with them. Retention is determined from the upstream listing for every host this model can reach. Neither is guessed.
Frequently asked questions
- Is gpt-oss-20b (free) available on FastMetal?
- Not at the moment. GPT-6.1 Sol, from the same lab, is available on the FastMetal API today.
- What is the context window of gpt-oss-20b (free)?
- 131,072 tokens, shared between the prompt and the response.