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Composer 1.5 vs gpt-oss-20b

Cursor Composer 1.5 vs OpenAI gpt-oss-20b — side-by-side specs.

Cursor
Composer 1.5
OpenAI
gpt-oss-20b
Overview
CompanyCursorOpenAI
Release dateFeb 8 2026Aug 5 2025
Model type
Open sourceNoYes
Specifications
Parameters
Context window
Benchmarks
Science reasoning
GPQA Diamond
Software engineering
SWE-Bench Verified
Multimodal understanding
MMMU
Timeline
Release gapgpt-oss-20b shipped 187 days before Composer 1.5

Which is better: Composer 1.5 or gpt-oss-20b?

Composer 1.5 and gpt-oss-20b do not have directly comparable benchmark scores published on GPQA Diamond, SWE-Bench Verified, or MMMU. gpt-oss-20b shipped 187 days before Composer 1.5, so benchmark comparisons should account for the intervening progress.

gpt-oss-20b is an open-source / open-weight model; Composer 1.5 is proprietary.

Direct benchmark comparisons are unavailable — at least one of these models has not published scores on GPQA Diamond, SWE-Bench Verified, or MMMU.

Frequently asked questions

When was Composer 1.5 released?
Composer 1.5 was released by Cursor on Feb 8 2026.
When was gpt-oss-20b released?
gpt-oss-20b was released by OpenAI on Aug 5 2025.
Is Composer 1.5 or gpt-oss-20b open source?
gpt-oss-20b is an open-source / open-weight model released by OpenAI. Composer 1.5 is a proprietary model released by Cursor.

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