The AI arena is free today

Open Superagent

Claude Sonnet 5.5 vs SWE-2

Claude Sonnet 5.5 leads the LLM Stats Score 57.9 to 47.9.

Anthropic · Cognition · Updated for 2026

Which is better?

Claude Sonnet 5.5 leads the overall LLM Stats Score 57.9 to 47.9, ranking #3 overall.

In the 3 individual benchmarks reported for both models, Claude Sonnet 5.5 wins 2; this is a narrower head-to-head signal than the composite indexes.

Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.

Choose Claude Sonnet 5.5

  • overall performance matters — it scores 57.9 and ranks #3 on LLM Stats
  • your work emphasizes coding — it leads those capability indexes
  • you value its reported benchmark strengths — it wins 2 of 3 exact shared results
  • you want the most recent training data — it shipped Sep 2026

Choose SWE-2

  • you are already invested in the Cognition ecosystem

At a glance

The differences that matter most.

Claude Sonnet 5.5
Anthropic
SWE-2
Cognition
Core performance indexes
LLM Stats Score
57.9
#3
47.9
#34
Reasoning
56.0
#2
45.5
#37
Coding
48.7
#2
38.7
#26
Agents
43.5
#4
35.6
#27
Cost, coverage & limits
Benchmark wins
2 of 3
1 of 3
Input price
$2.00 / M
— / M
Output price
$10.00 / M
— / M
Context window
1,000,000
—

Capability indexes

Additional strengths measured across groups of related public benchmarks

1 shared
Index
Claude Sonnet 5.5
SWE-2
Tool use
35.9#2
26.2#38
Conservative TrueSkill rating · higher is betterHow scores work

Individual benchmarks

47 reported for Claude Sonnet 5.5 · 4 for SWE-2

3 shared

Claude Sonnet 5.5 outperforms in 2 benchmarks (FrontierCode 1.1, Terminal-Bench 4.0), while SWE-2 is better at 1 benchmark (DeepSWE 1.1).

Claude Sonnet 5.5 shows notably better performance in the majority of benchmarks.

Fri Nov 06 2026 • llm-stats.com

Human preference

Blind head-to-head votes and playground preference scores

Context Window

Maximum input and output token capacity

Only Claude Sonnet 5.5 specifies input context (1,000,000 tokens). Only Claude Sonnet 5.5 specifies output context (128,000 tokens).

Anthropic
Claude Sonnet 5.5
Input1,000,000 tokens
Output128,000 tokens
Cognition
SWE-2
Input- tokens
Output- tokens
Fri Nov 06 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Claude Sonnet 5.5 supports multimodal inputs, whereas SWE-2 does not.

Claude Sonnet 5.5 can handle both text and other forms of data like images, making it suitable for multimodal applications.

Claude Sonnet 5.5

Text
Images
Audio
Video

SWE-2

Text
Images
Audio
Video

License

Usage and distribution terms

Both models are licensed under proprietary licenses.

Both models have usage restrictions defined by their respective organizations.

Claude Sonnet 5.5

Proprietary

Closed source

SWE-2

Proprietary

Closed source

Release Timeline

When each model was launched

Claude Sonnet 5.5 was released on 2026-09-28, while SWE-2 was released on 2026-09-10.

Claude Sonnet 5.5 is 1 month newer than SWE-2.

Claude Sonnet 5.5

Sep 28, 2026

1 months ago

2w newer
SWE-2

Sep 10, 2026

1 months ago

Knowledge Cutoff

When training data ends

Claude Sonnet 5.5 has a documented knowledge cutoff of 2026-06-01, while SWE-2's cutoff date is not specified.

We can confirm Claude Sonnet 5.5's training data extends to 2026-06-01, but cannot make a direct comparison without SWE-2's cutoff date.

Claude Sonnet 5.5

Jun 2026

SWE-2

—

Outputs Comparison

Notice missing or incorrect data?

Judge for yourself.

Run your own prompts against Claude Sonnet 5.5 and SWE-2 side-by-side, then vote on the output you prefer.

Claude Sonnet 5.5
✓ Preferred
SWE-2
Open in Playground

FAQ

Common questions about Claude Sonnet 5.5 vs SWE-2.

Which is better, Claude Sonnet 5.5 or SWE-2?

Claude Sonnet 5.5 leads the LLM Stats Score 57.9 to 47.9. Claude Sonnet 5.5 is made by Anthropic and SWE-2 is made by Cognition. The best choice depends on your use case — compare their capability indexes, individual benchmarks, pricing, and limits above.

How does Claude Sonnet 5.5 compare to SWE-2 in benchmarks?

Claude Sonnet 5.5 scores BenchCAD (with Python tool): 96.3%, ArXivMath (with tools): 95.2%, Global-MMLU: 92.1%, MILU: 91.6%, SWE-bench Multilingual: 90.3%. SWE-2 scores Terminal-Bench 2.1: 92.8%, DeepSWE 1.1: 73.0%, FrontierCode 1.1: 50.0%, Terminal-Bench 4.0: 27.3%.

What are the context window sizes for Claude Sonnet 5.5 and SWE-2?

Claude Sonnet 5.5 supports 1.0M tokens and SWE-2 supports an unknown number of tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Claude Sonnet 5.5 and SWE-2?

Key differences include LLM Stats Score (57.9 vs 47.9), multimodal support (yes vs no). See the full comparison above for benchmark-by-benchmark results.

Who makes Claude Sonnet 5.5 and SWE-2?

Claude Sonnet 5.5 is developed by Anthropic and SWE-2 is developed by Cognition.

Related comparisons