Model Comparison

Claude Sonnet 5 vs Seed 2.1 ProWhich is better in 2026?

Claude Sonnet 5 shows notably better performance in the majority of benchmarks.

Verdict: Claude Sonnet 5 vs Seed 2.1 Pro — which is better?

Claude Sonnet 5 (by Anthropic) and Seed 2.1 Pro (by ByteDance) are two of the AI models people compare most. Here is how they stack up on benchmarks, price and capabilities, and which one to pick in 2026.

Claude Sonnet 5 outperforms in 4 benchmarks (CharXiv-R, Humanity's Last Exam, SWE-Bench Pro, Toolathlon), while Seed 2.1 Pro is better at 2 benchmarks (BrowseComp, OfficeQA Pro). Claude Sonnet 5 shows notably better performance in the majority of benchmarks.

Choose Claude Sonnet 5 if…

  • you want the strongest raw capability — it leads on 4 of 6 shared benchmarks
  • you want the most recent training data — it shipped Jun 2026

Choose Seed 2.1 Pro if…

  • you are already invested in the ByteDance ecosystem

Performance Benchmarks

Comparative analysis across standard metrics

6 benchmarks

Claude Sonnet 5 outperforms in 4 benchmarks (CharXiv-R, Humanity's Last Exam, SWE-Bench Pro, Toolathlon), while Seed 2.1 Pro is better at 2 benchmarks (BrowseComp, OfficeQA Pro).

Claude Sonnet 5 shows notably better performance in the majority of benchmarks.

Fri Jul 17 2026 • llm-stats.com

Arena Performance

Human preference votes

Context Window

Maximum input and output token capacity

Only Claude Sonnet 5 specifies input context (1,000,000 tokens). Only Claude Sonnet 5 specifies output context (64,000 tokens).

Anthropic
Claude Sonnet 5
Input1,000,000 tokens
Output64,000 tokens
ByteDance
Seed 2.1 Pro
Input- tokens
Output- tokens
Fri Jul 17 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both Claude Sonnet 5 and Seed 2.1 Pro support multimodal inputs.

They are both capable of processing various types of data, offering versatility in application.

Claude Sonnet 5

Text
Images
Audio
Video

Seed 2.1 Pro

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

Proprietary

Closed source

Seed 2.1 Pro

Proprietary

Closed source

Release Timeline

When each model was launched

Claude Sonnet 5 was released on 2026-06-30, while Seed 2.1 Pro was released on 2026-06-24.

Claude Sonnet 5 is 0 month newer than Seed 2.1 Pro.

Claude Sonnet 5

Jun 30, 2026

2 weeks ago

6d newer
Seed 2.1 Pro

Jun 24, 2026

3 weeks ago

Knowledge Cutoff

When training data ends

Neither model specifies a knowledge cutoff date.

Unable to compare the recency of their training data.

No cutoff dates available

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

Anthropic
Larger context window (1,000,000 tokens)
Higher CharXiv-R score (88.3% vs 86.4%)
Higher Humanity's Last Exam score (57.4% vs 55.7%)
Higher SWE-Bench Pro score (63.2% vs 57.5%)
Higher Toolathlon score (54.3% vs 50.6%)
ByteDance
Higher BrowseComp score (86.2% vs 84.7%)
Higher OfficeQA Pro score (72.2% vs 59.4%)

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against Claude Sonnet 5 and Seed 2.1 Pro side-by-side, then vote on the output you prefer.

Claude Sonnet 5
✓ Preferred
Seed 2.1 Pro
Open in Playground
AI Model Comparison Table
Feature
Anthropic
Claude Sonnet 5
ByteDance
Seed 2.1 Pro

FAQ

Common questions about Claude Sonnet 5 vs Seed 2.1 Pro.

Which is better, Claude Sonnet 5 or Seed 2.1 Pro?

Claude Sonnet 5 shows notably better performance in the majority of benchmarks. Claude Sonnet 5 is made by Anthropic and Seed 2.1 Pro is made by ByteDance. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does Claude Sonnet 5 compare to Seed 2.1 Pro in benchmarks?

Claude Sonnet 5 scores CharXiv-R: 88.3%, ChartMuseum: 86.7%, SWE-Bench Verified: 85.2%, BrowseComp: 84.7%, GDP.pdf: 81.6%. Seed 2.1 Pro scores CharXiv-D: 95.5%, MathVision: 94.5%, MathVista: 90.7%, MathVerse: 89.7%, Video-MME: 89.2%.

What are the context window sizes for Claude Sonnet 5 and Seed 2.1 Pro?

Claude Sonnet 5 supports 1.0M tokens and Seed 2.1 Pro supports an unknown number of tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

Who makes Claude Sonnet 5 and Seed 2.1 Pro?

Claude Sonnet 5 is developed by Anthropic and Seed 2.1 Pro is developed by ByteDance.

Related comparisons