openai

OpenAI: gpt-oss-20b (free)

by openai No longer free

Last seen as free: Aug 21, 2026

OpenRouter
Tools Reasoning Long Context

Availability

Available 85 of 85 tracked days. Daily snapshots show whether this model was accessible as a free model on OpenRouter.

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OpenAI: gpt-oss-20b (free)24

About

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...

Specifications

Context Length 131K
Max Output Tokens 33K
Modality text->text
Input text
Output text
Supported Parameters frequency_penalty, include_reasoning, logprobs, max_tokens, presence_penalty, reasoning, reasoning_effort, repetition_penalty, response_format, seed, stop, structured_outputs, temperature, tool_choice, tools, top_k, top_logprobs, top_p
Content Moderation No

Error Rate

Based on feedback reported by Free LLM Router users. Error rate reflects the percentage of requests that encountered issues such as rate limiting, unavailability, or errors. Learn more.

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Model 1h 6h 24h 7d 30d
OpenAI: gpt-oss-20b (free) - - - 100.0% 100.0%

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Frequently Asked Questions

Is OpenAI: gpt-oss-20b (free) still free to use?

OpenAI: gpt-oss-20b (free) is no longer available as a free model on OpenRouter.

What is the context window for OpenAI: gpt-oss-20b (free)?

OpenAI: gpt-oss-20b (free) supports a context window of 131K tokens (131,072 tokens).

What is the maximum output length for OpenAI: gpt-oss-20b (free)?

OpenAI: gpt-oss-20b (free) can generate up to 33K tokens (32,768 tokens) per response.

Does OpenAI: gpt-oss-20b (free) support function calling (tools)?

Yes, OpenAI: gpt-oss-20b (free) supports function calling / tool use, enabling it to interact with external APIs and services.

Does OpenAI: gpt-oss-20b (free) support reasoning?

Yes, OpenAI: gpt-oss-20b (free) supports reasoning capabilities, allowing it to show its step-by-step thought process.