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Composer 1.5 vs DeepSeek V3.1 Terminus

Cursor Composer 1.5 vs DeepSeek DeepSeek V3.1 Terminus — side-by-side specs.

Cursor
Composer 1.5
DeepSeek
DeepSeek V3.1 Terminus
Overview
CompanyCursorDeepSeek
Release dateFeb 8 2026Sep 22 2025
Model type
Open sourceNoYes
Specifications
Parameters
Context window
Benchmarks
Science reasoning
GPQA Diamond
Software engineering
SWE-Bench Verified
Multimodal understanding
MMMU
Timeline
Release gapDeepSeek V3.1 Terminus shipped 139 days before Composer 1.5

Which is better: Composer 1.5 or DeepSeek V3.1 Terminus?

Composer 1.5 and DeepSeek V3.1 Terminus do not have directly comparable benchmark scores published on GPQA Diamond, SWE-Bench Verified, or MMMU. DeepSeek V3.1 Terminus shipped 139 days before Composer 1.5, so benchmark comparisons should account for the intervening progress.

DeepSeek V3.1 Terminus 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 DeepSeek V3.1 Terminus released?
DeepSeek V3.1 Terminus was released by DeepSeek on Sep 22 2025.
Is Composer 1.5 or DeepSeek V3.1 Terminus open source?
DeepSeek V3.1 Terminus is an open-source / open-weight model released by DeepSeek. Composer 1.5 is a proprietary model released by Cursor.

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