GLM-5.3-Flash vs Grok-4 Heavy
GLM-5.3-Flash significantly outperforms across most benchmarks.
Zhipu AI · xAI · Updated for 2026
Which is better?
GLM-5.3-Flash outperforms in 1 benchmarks (Humanity's Last Exam), while Grok-4 Heavy is better at 0 benchmarks. GLM-5.3-Flash significantly outperforms across most benchmarks.
Based on current benchmark, pricing, and model metadata for 2026.
Choose GLM-5.3-Flash
- you want the strongest raw capability — it leads on 1 of 1 shared benchmarks
- you need open weights you can self-host or fine-tune
Choose Grok-4 Heavy
- you are already invested in the xAI ecosystem
At a glance
The differences that matter most.
Performance Benchmarks
Comparative analysis across standard metrics
GLM-5.3-Flash outperforms in 1 benchmarks (Humanity's Last Exam), while Grok-4 Heavy is better at 0 benchmarks.
GLM-5.3-Flash significantly outperforms across most benchmarks.
Arena Performance
Playground indexes and blind 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).
Input Capabilities
Supported data types and modalities
Both GLM-5.3-Flash and Grok-4 Heavy support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
GLM-5.3-Flash
Grok-4 Heavy
License
Usage and distribution terms
GLM-5.3-Flash is licensed under MIT, while Grok-4 Heavy uses a proprietary license.
License differences may affect how you can use these models in commercial or open-source projects.
MIT
Open weights
Proprietary
Closed source
Release Timeline
When each model was launched
GLM-5.3-Flash was released on 2026-08-26, while Grok-4 Heavy's release date is not specified.
We can confirm GLM-5.3-Flash's release timeline, but cannot make a direct age comparison without Grok-4 Heavy's release date.
Aug 26, 2026
0 days ago
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Knowledge Cutoff
When training data ends
Grok-4 Heavy has a documented knowledge cutoff of 2024-12-31, while GLM-5.3-Flash's cutoff date is not specified.
We can confirm Grok-4 Heavy's training data extends to 2024-12-31, but cannot make a direct comparison without GLM-5.3-Flash's cutoff date.
—
Dec 2024
Outputs Comparison
Judge for yourself.
Run your own prompts against GLM-5.3-Flash and Grok-4 Heavy side-by-side, then vote on the output you prefer.
FAQ
Common questions about GLM-5.3-Flash vs Grok-4 Heavy.