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OpenAI: gpt-oss-20b

openai/gpt-oss-20b

Model weights
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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.

Modalities

In / Out Price

$0.03 / $0.13per 1M

Context

131K

Released

Aug 5, 2025

Knowledge Cutoff

Jun 2024

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About OpenAI: gpt-oss-20b

OpenRouter makes OpenAI: gpt-oss-20b available through a unified, OpenAI-compatible API using the model ID openai/gpt-oss-20b. Requests can be routed across 11 providers, including CoreWeave, DeepInfra, Parasail, Phala, NovitaAI, SiliconFlow, Together, Amazon Bedrock (EU) and 3 more, with automatic failover when an endpoint is unavailable.

OpenAI: gpt-oss-20b accepts text and returns text. It has a 131,072-token context window and a maximum output of 131,072 tokens.

On OpenRouter, OpenAI: gpt-oss-20b costs $0.03/M input tokens and $0.13/M output tokens, with separate rates for Cache Read at $0.03/M tokens. Effective pricing can be lower when prompt caching applies. It was released on August 5, 2025; its knowledge cutoff is June 30, 2024.

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Frequently asked questions

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.

gpt-oss-20b costs $0.03/M input tokens and $0.13/M output tokens, with separate rates for Cache Read at $0.03/M tokens.

gpt-oss-20b has a 131,072 token context window. It supports up to 131,072 completion tokens.

Yes. gpt-oss-20b accepts tools and tool_choice for function calling. It also supports structured outputs via a JSON schema in response_format.

gpt-oss-20b is served by 11 providers on OpenRouter: CoreWeave, DeepInfra, Parasail, Phala, NovitaAI, SiliconFlow, Together, Amazon Bedrock (EU) and 3 more. Requests are routed to the best available provider, with automatic failover to the others, and you can pin or exclude providers with provider routing.

gpt-oss-20b was released on August 5, 2025. Its knowledge cutoff is June 30, 2024.