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OpenAI: gpt-oss-20b

openai/gpt-oss-20b:free

Model weights

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

Price

Free

Context

131K

Released

Aug 5, 2025

Knowledge Cutoff

Jun 2024

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Activity

Token volume and request traffic to this model over time.

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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.

Yes. The pricing shown on this page for gpt-oss-20b is zero, so you are not charged for prompt or completion tokens. Free endpoints are rate limited — see the rate limit docs.

gpt-oss-20b has a 131,072 token context window.

GPT-5.6 Luna Pro, GPT-5.6 Luna, GPT-5.6 Terra Pro and 55 more are other text models from OpenAI.

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