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GLM-5.3-Flash vs Seed 2.1 Pro

GLM-5.3-Flash leads the LLM Stats Score 51.6 to 47.0.

Zhipu AI · ByteDance · Updated for 2026

Which is better?

GLM-5.3-Flash leads the overall LLM Stats Score 51.6 to 47.0, ranking #11 overall.

The models split the 8 individual benchmarks reported for both models evenly.

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

Choose GLM-5.3-Flash

  • overall performance matters — it scores 51.6 and ranks #11 on LLM Stats
  • your work emphasizes agents — it leads those capability indexes
  • you want the most recent training data — it shipped Aug 2026
  • you need open weights you can self-host or fine-tune

Choose Seed 2.1 Pro

  • you are already invested in the ByteDance ecosystem

At a glance

The differences that matter most.

GLM-5.3-Flash
Zhipu AI
Seed 2.1 Pro
ByteDance
Core performance indexes
LLM Stats Score
51.6
#11
47.0
#20
Reasoning
50.3
#13
47.9
#18
Coding
37.8
#22
36.0
#25
Agents
39.1
#9
33.1
#22
Cost, coverage & limits
Benchmark wins
4 of 8
4 of 8
Input price
$0.15 / M
— / M
Output price
$0.50 / M
— / M
Context window
1,048,576
—

Capability indexes

Additional strengths measured across groups of related public benchmarks

3 shared
Index
GLM-5.3-Flash
Seed 2.1 Pro
Vision
32.0#21
34.9#10
Tool use
34.2#4
27.9#17
Multimodal
30.9#24
37.7#5
Conservative TrueSkill rating · higher is betterHow scores work

Individual benchmarks

15 reported for GLM-5.3-Flash · 94 for Seed 2.1 Pro

8 shared

GLM-5.3-Flash outperforms in 4 benchmarks (CharXiv-R, NL2Repo, Terminal-Bench 2.1, Toolathlon), while Seed 2.1 Pro is better at 4 benchmarks (Agents' Last Exam, BabyVision, Humanity's Last Exam, OfficeQA Pro).

Both models are evenly matched across the benchmarks.

Fri Aug 28 2026 • llm-stats.com

Human preference

Blind head-to-head votes and playground preference scores

Context Window

Maximum input and output token capacity

Only GLM-5.3-Flash specifies input context (1,048,576 tokens). Only GLM-5.3-Flash specifies output context (131,072 tokens).

Zhipu AI
GLM-5.3-Flash
Input1,048,576 tokens
Output131,072 tokens
ByteDance
Seed 2.1 Pro
Input- tokens
Output- tokens
Fri Aug 28 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Both GLM-5.3-Flash and Seed 2.1 Pro support multimodal inputs.

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

GLM-5.3-Flash

Text
Images
Audio
Video

Seed 2.1 Pro

Text
Images
Audio
Video

License

Usage and distribution terms

GLM-5.3-Flash is licensed under MIT, while Seed 2.1 Pro uses a proprietary license.

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

GLM-5.3-Flash

MIT

Open weights

Seed 2.1 Pro

Proprietary

Closed source

Release Timeline

When each model was launched

GLM-5.3-Flash was released on 2026-08-26, while Seed 2.1 Pro was released on 2026-06-24.

GLM-5.3-Flash is 2 months newer than Seed 2.1 Pro.

GLM-5.3-Flash

Aug 26, 2026

2 days ago

2mo newer
Seed 2.1 Pro

Jun 24, 2026

2 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→

Judge for yourself.

Run your own prompts against GLM-5.3-Flash and Seed 2.1 Pro side-by-side, then vote on the output you prefer.

GLM-5.3-Flash
✓ Preferred
Seed 2.1 Pro
Open in Playground

FAQ

Common questions about GLM-5.3-Flash vs Seed 2.1 Pro.

Which is better, GLM-5.3-Flash or Seed 2.1 Pro?

GLM-5.3-Flash leads the LLM Stats Score 51.6 to 47.0. GLM-5.3-Flash is made by Zhipu AI and Seed 2.1 Pro is made by ByteDance. The best choice depends on your use case — compare their capability indexes, individual benchmarks, pricing, and limits above.

How does GLM-5.3-Flash compare to Seed 2.1 Pro in benchmarks?

GLM-5.3-Flash scores CharXiv-R: 89.4%, Terminal-Bench 2.1: 84.3%, MMVU: 80.5%, Toolathlon: 78.4%, Chartography: 78.0%. 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 GLM-5.3-Flash and Seed 2.1 Pro?

GLM-5.3-Flash 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.

What are the main differences between GLM-5.3-Flash and Seed 2.1 Pro?

Key differences include LLM Stats Score (51.6 vs 47.0), licensing (MIT vs Proprietary). See the full comparison above for benchmark-by-benchmark results.

Who makes GLM-5.3-Flash and Seed 2.1 Pro?

GLM-5.3-Flash is developed by Zhipu AI and Seed 2.1 Pro is developed by ByteDance.

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