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Claude Sonnet 4.5 vs DeepSeek V3.1 Terminus

3 vs 0 benchmarks won

Anthropic
Claude Sonnet 4.5
DeepSeek
DeepSeek V3.1 Terminus
Overview
CompanyAnthropicDeepSeek
Release dateSep 29 2025Sep 22 2025
Model type
Open sourceNoYes
Specifications
Parameters
Context window
Benchmarks
Science reasoning
GPQA Diamond
83.4%
Software engineering
SWE-Bench Verified
77.2%
Multimodal understanding
MMMU
68%
Timeline
Release gapDeepSeek V3.1 Terminus shipped 7 days before Claude Sonnet 4.5

Which is better: Claude Sonnet 4.5 or DeepSeek V3.1 Terminus?

Claude Sonnet 4.5 leads DeepSeek V3.1 Terminus on 3 of the tracked benchmarks (GPQA Diamond, SWE-Bench Verified, MMMU). DeepSeek V3.1 Terminus shipped 7 days before Claude Sonnet 4.5, so benchmark comparisons should account for the intervening progress.

DeepSeek V3.1 Terminus is an open-source / open-weight model; Claude Sonnet 4.5 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 Claude Sonnet 4.5 released?
Claude Sonnet 4.5 was released by Anthropic on Sep 29 2025.
When was DeepSeek V3.1 Terminus released?
DeepSeek V3.1 Terminus was released by DeepSeek on Sep 22 2025.
Is Claude Sonnet 4.5 or DeepSeek V3.1 Terminus open source?
DeepSeek V3.1 Terminus is an open-source / open-weight model released by DeepSeek. Claude Sonnet 4.5 is a proprietary model released by Anthropic.

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