GLM-5.1
An incremental refinement of GLM-5 that tightened instruction-following and coding. It is a dependable, low-cost open-weight option for mainstream tasks.
At a glance
Released
Mar 4, 2026
Provider
Zhipu AI
Context window
200,000 tokens
Max output
32,000 tokens
Modalities
Text → text
Knowledge cutoff
November 2025
API model ID
glm-5.1License
Open weights (MIT)
Pricing
Standard
Input$1.40 / 1M
Output$4.40 / 1M
A typical 1,500-token prompt with a 650-token answer costs ≈ $0.005 on the standard tier. Run your own prompt through the calculator →
What's new vs the previous model
Compared withGLM-5 (December 2025)
- Cleaner instruction-following and formatting than GLM-5
- Better structured-output reliability
- Shorter max output than later 5.x releases
Best use cases
Everyday reasoning
Covers routine analysis and Q&A at low cost.
Content drafting
Generates solid long-form drafts for editing.
On-prem deployment
Runs locally under MIT for privacy-sensitive workloads.
Strengths & limitations
Strengths
- Reliable formatting
- Open weights
- Inexpensive
Limitations
- Older cutoff
- Outclassed by newer 5.x models
How to test it
- No-code: open chat.z.ai and pick GLM-5.1 from the model switcher — no API key needed.
- Playground: sign in to the Z.ai API console and run prompts in the workbench, then copy the generated code.
- API: create a key in the Z.ai API console and call the API (example below).
curl https://api.z.ai/api/paas/v4/chat/completions \
# OpenAI-compatible endpoint
-H "Authorization: Bearer $API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "glm-5.1",
"messages": [{"role": "user", "content": "Explain tokenization in one paragraph."}]
}'