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Claude Sonnet 4.5 vs DeepSeek Chat (R1-based)

3 vs 0 benchmarks won

Anthropic
Claude Sonnet 4.5
DeepSeek
DeepSeek Chat (R1-based)
Overview
CompanyAnthropicDeepSeek
Release dateSep 29 2025Jan 20 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 Chat (R1-based) shipped 252 days before Claude Sonnet 4.5

Which is better: Claude Sonnet 4.5 or DeepSeek Chat (R1-based)?

Claude Sonnet 4.5 leads DeepSeek Chat (R1-based) on 3 of the tracked benchmarks (GPQA Diamond, SWE-Bench Verified, MMMU). DeepSeek Chat (R1-based) shipped 252 days before Claude Sonnet 4.5, so benchmark comparisons should account for the intervening progress.

DeepSeek Chat (R1-based) 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 Chat (R1-based) released?
DeepSeek Chat (R1-based) was released by DeepSeek on Jan 20 2025.
Is Claude Sonnet 4.5 or DeepSeek Chat (R1-based) open source?
DeepSeek Chat (R1-based) 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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