Grok 4 Fast vs GLM-5.1
xAI Grok 4 Fast | Z.ai GLM-5.1 | |
|---|---|---|
| Overview | ||
| Company | xAI | Z.ai |
| Release date | Sep 2025 | Apr 7 2026 |
| Access | Proprietary | Open Weight |
| Specifications | ||
Parameters | — | 744B |
Context window | — | 200k |
| Benchmarks | ||
Agentic terminal coding Terminal-Bench 2.0Can the AI work in a command-line terminal — running commands and finishing technical setup tasks the way a developer would? (Version 2.0 of the test.) Higher is better. | — | 63.5% |
Web browsing BrowseCompCan the AI browse the web and track down hard-to-find answers? Higher is better. | — | 68% |
Science GPQA DiamondGraduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better. | — | 86.2% |
| Timeline | ||
| Release gap | Grok 4 Fast shipped 218 days before GLM-5.1 | |
Which is better: Grok 4 Fast or GLM-5.1?
Grok 4 Fast and GLM-5.1 don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. Grok 4 Fast shipped 218 days before GLM-5.1, so benchmark comparisons should account for the intervening progress.
Grok 4 Fast is proprietary, while GLM-5.1 is open weight.
Direct benchmark comparisons are unavailable — Grok 4 Fast and GLM-5.1 don't publish scores on any of the same benchmarks.
Frequently asked questions
Grok 4 Fast was released by xAI on Sep 2025.
GLM-5.1 was released by Z.ai on Apr 7 2026.
Grok 4 Fast is a proprietary model released by xAI. GLM-5.1 is an open weight model released by Z.ai.
Other comparisons
Grok 4 Fast vs Claude Fable 5GLM-5.1 vs Claude Fable 5Grok 4 Fast vs GPT-5.6 SolGLM-5.1 vs GPT-5.6 SolGrok 4 Fast vs Gemini OmniGLM-5.1 vs Gemini OmniGrok 4 Fast vs Muse SparkGLM-5.1 vs Muse SparkGrok 4 Fast vs DeepSeek-V4-ProGLM-5.1 vs DeepSeek-V4-ProGrok 4 Fast vs Mistral Medium 3.5GLM-5.1 vs Mistral Medium 3.5