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AI model reference · 2026

gpt-oss-20b

OpenAI: gpt-oss-20b logoOpenAIModel details, evidence, and API facts

gpt-oss-20b is an open-weight 21B parameter model released by OpenAI under the Apache 2.0 license.

Text generation
Reasoning
Provider endpoint accepts tool parameters
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Context window
131,072 tokens
Maximum output
131,072 tokens
Base provider API input
$0.03 / 1M tokens
Base provider API rate
Published evidence
0 benchmarks, 1 Arena result

Overview

About gpt-oss-20b

A concise catalog overview. Technical limits and published evaluation evidence are listed separately below.

gpt-oss-20b is an open-weight 21B parameter model released by OpenAI under the Apache 2.0 license.

text
reasoning

Published evaluations

Benchmark results

Only results mapped to this exact model and backed by a named source appear here. Different evaluation protocols are not treated as interchangeable.

No reviewed benchmark result is available for this exact model yet. We leave this section empty instead of assigning a nearby model’s score.

Human preference

Arena results

Arena scores come from blind human preference votes. They are reported separately from task benchmarks and are not used as substitutes for missing benchmark results.

Arena results for gpt-oss-20b
CategoryScoreRankVotesStatus
Arena TextBlind human preference score for text responses.1,318±6#24710,669Published

Technical reference

Specifications and API facts

Technical limits and reference provider prices come from the current catalog unless a reviewed external source is listed. Missing values stay marked as unavailable.

Model
Provider
OpenAI
Release date
Not available in reviewed sources
Catalog added
Aug 5, 2025
Context window
131,072 tokens
Maximum output
131,072 tokens
Knowledge cutoff
2024-06-30
License
Not available in reviewed sources
Capabilities and API
Input types
Text
Output types
Text
Reasoning
Supported
Provider endpoint tool parameters
Accepts tool parameters
Base provider API input
$0.03 / 1M tokens
Base provider cached input
$0.03 / 1M tokens
Base provider API output
$0.13 / 1M tokens

These are reference provider API rates, not Writingmate checkout charges. Access in Writingmate follows the allowances of your Writingmate plan.

Provenance

Sources and update status

Source links are attached to the facts and evaluations they support. Catalog-only values are not presented as independently verified claims.

Evidence last updated Aug 23, 2026.

Catalog record updated Aug 5, 2025.

Catalog-added dates describe when a model entered the catalog, not necessarily its public release date.

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