Model Comparison

Seed 2.1 Pro vs GLM-5.1Which is better in 2026?

Seed 2.1 Pro significantly outperforms across most benchmarks.

Verdict: Seed 2.1 Pro vs GLM-5.1 — which is better?

Seed 2.1 Pro (by ByteDance) and GLM-5.1 (by Zhipu AI) 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.

Seed 2.1 Pro outperforms in 6 benchmarks (BrowseComp, CyberGym, Humanity's Last Exam, MCP Atlas, NL2Repo, Toolathlon), while GLM-5.1 is better at 1 benchmark (SWE-Bench Pro). Seed 2.1 Pro significantly outperforms across most benchmarks.

Choose Seed 2.1 Pro if…

  • you want the strongest raw capability — it leads on 6 of 7 shared benchmarks
  • you want the most recent training data — it shipped Jun 2026

Choose GLM-5.1 if…

  • you need open weights you can self-host or fine-tune

Performance Benchmarks

Comparative analysis across standard metrics

7 benchmarks

Seed 2.1 Pro outperforms in 6 benchmarks (BrowseComp, CyberGym, Humanity's Last Exam, MCP Atlas, NL2Repo, Toolathlon), while GLM-5.1 is better at 1 benchmark (SWE-Bench Pro).

Seed 2.1 Pro significantly outperforms across most benchmarks.

Fri Jul 17 2026 • llm-stats.com

Arena Performance

Human preference votes

Context Window

Maximum input and output token capacity

Only GLM-5.1 specifies input context (200,000 tokens). Only GLM-5.1 specifies output context (128,000 tokens).

ByteDance
Seed 2.1 Pro
Input- tokens
Output- tokens
Zhipu AI
GLM-5.1
Input200,000 tokens
Output128,000 tokens
Fri Jul 17 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Seed 2.1 Pro supports multimodal inputs, whereas GLM-5.1 does not.

Seed 2.1 Pro can handle both text and other forms of data like images, making it suitable for multimodal applications.

Seed 2.1 Pro

Text
Images
Audio
Video

GLM-5.1

Text
Images
Audio
Video

License

Usage and distribution terms

Seed 2.1 Pro is licensed under a proprietary license, while GLM-5.1 uses MIT.

License differences may affect how you can use these models in commercial or open-source projects.

Seed 2.1 Pro

Proprietary

Closed source

GLM-5.1

MIT

Open weights

Release Timeline

When each model was launched

Seed 2.1 Pro was released on 2026-06-24, while GLM-5.1 was released on 2026-04-07.

Seed 2.1 Pro is 3 months newer than GLM-5.1.

Seed 2.1 Pro

Jun 24, 2026

3 weeks ago

2mo newer
GLM-5.1

Apr 7, 2026

3 months 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

ByteDance
Supports multimodal inputs
Higher BrowseComp score (86.2% vs 79.3%)
Higher CyberGym score (70.2% vs 68.7%)
Higher Humanity's Last Exam score (55.7% vs 52.3%)
Higher MCP Atlas score (83.8% vs 71.8%)
Higher NL2Repo score (47.0% vs 42.7%)
Higher Toolathlon score (50.6% vs 40.7%)
Zhipu AI
Larger context window (200,000 tokens)
Has open weights
Higher SWE-Bench Pro score (58.4% vs 57.5%)

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against Seed 2.1 Pro and GLM-5.1 side-by-side, then vote on the output you prefer.

Seed 2.1 Pro
✓ Preferred
GLM-5.1
Open in Playground
AI Model Comparison Table
Feature
ByteDance
Seed 2.1 Pro
Zhipu AI
GLM-5.1

FAQ

Common questions about Seed 2.1 Pro vs GLM-5.1.

Which is better, Seed 2.1 Pro or GLM-5.1?

Seed 2.1 Pro significantly outperforms across most benchmarks. Seed 2.1 Pro is made by ByteDance and GLM-5.1 is made by Zhipu AI. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does Seed 2.1 Pro compare to GLM-5.1 in benchmarks?

Seed 2.1 Pro scores CharXiv-D: 95.5%, MathVision: 94.5%, MathVista: 90.7%, MathVerse: 89.7%, Video-MME: 89.2%. GLM-5.1 scores Vending-Bench 2: 100.0%, AIME 2026: 95.3%, HMMT 2025: 94.0%, GPQA: 86.2%, IMO-AnswerBench: 83.8%.

What are the context window sizes for Seed 2.1 Pro and GLM-5.1?

Seed 2.1 Pro supports an unknown number of tokens and GLM-5.1 supports 200K tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Seed 2.1 Pro and GLM-5.1?

Key differences include multimodal support (yes vs no), licensing (Proprietary vs MIT). See the full comparison above for benchmark-by-benchmark results.

Who makes Seed 2.1 Pro and GLM-5.1?

Seed 2.1 Pro is developed by ByteDance and GLM-5.1 is developed by Zhipu AI.

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