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Compare performance benchmarks, coding intelligence, reasoning evaluations, context limits, and API economics between Claude Sonnet 5.5 (Anthropic) and DeepSeek V4.1 Flash 1017 (DeepSeek).
| Metric / Capability | Claude Sonnet 5.5 | DeepSeek V4.1 Flash 1017 |
|---|---|---|
| Developer / Organization | Anthropic | DeepSeek |
| Release Date | 2026-09-28 | 2026-10-17 |
| Deployment / Weights | Proprietary Cloud API | Open Weights |
| Context Window | 1M tokens (1,000,000 tokens) | 1.0M tokens (1,048,576 tokens) |
| Input Pricing (/1M Tokens) | $2 | Free (Open Weights) |
| Output Pricing (/1M Tokens) | $10 | Free (Open Weights) |
| Benchmark / Domain | Claude Sonnet 5.5 | DeepSeek V4.1 Flash 1017 | Advantage |
|---|---|---|---|
Artificial Analysis Intelligence Index Composite index aggregating 10+ evaluations of general reasoning and knowledge. | 56.0% | 39.5% | Claude Sonnet 5.5 (+42%) |
Artificial Analysis Coding Agent Index v2.0 Composite index of coding-agent systems (model + harness) across FrontierCode v1.1, SWE-Atlas-QnA, and Terminal-Bench v4. | 59.3% | 46.3% | Claude Sonnet 5.5 (+28%) |
SWE-bench Pro Harder, contamination-resistant successor to SWE-bench spanning multiple languages. | 81.3% | — | — |
Terminal-Bench 4.0 Sandboxed command-line tasks requiring shell and file-system operation. | 70.6% | 42.3% | Claude Sonnet 5.5 (+67%) |
ARC-AGI-2 Novel visual grid puzzles requiring abstract rule induction. | 83.9% | — | — |
GPQA Diamond Graduate-level physics, chemistry, and biology questions written by domain experts. | — | 90.9% | — |
Humanity's Last Exam Expert-written questions across hundreds of disciplines designed to resist saturation. | 56.9% | 42.6% | Claude Sonnet 5.5 (+34%) |
FrontierMath v2 (Tiers 1-3) Unpublished, research-level mathematics problems across Tiers 1-3. | 88.8% | 67.4% | Claude Sonnet 5.5 (+32%) |
Design Arena ELO Human-preference ELO across UI, 3D, data-visualization, and game-dev generations. | 1413 | 1362 | Claude Sonnet 5.5 (+4%) |
Claude Sonnet 5.5 leads across 6 evaluated benchmarks compared to 0 for DeepSeek V4.1 Flash 1017, showing notable advantages in Artificial Analysis Intelligence Index, Artificial Analysis Coding Agent Index v2.0, Terminal-Bench 4.0.
DeepSeek V4.1 Flash 1017 has the larger context capacity of 1.0M tokens (1,048,576 tokens), compared to 1M tokens for Claude Sonnet 5.5.
DeepSeek V4.1 Flash 1017 is more economical. Input tokens cost $Free (Open Weights)/M tokens compared to $2/M tokens for Claude Sonnet 5.5.
Claude Sonnet 5.5 is a proprietary cloud API. DeepSeek V4.1 Flash 1017 is an open-weights model.
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