GLM 5.1
GLM 5.1 advances Z.ai's GLM-5 generation with a focus on long-horizon autonomous coding. It can work independently on a single task for over eight hours, planning, executing, and iterating until it delivers engineering-grade results.
import { streamText } from 'ai'
const result = streamText({ model: 'zai/glm-5.1', prompt: 'Why is the sky blue?'})Playground
Try out GLM 5.1 by Z.ai. Usage is billed to your team at API rates. Free users (those who haven't made a payment) get $5 of credits every 30 days.
Providers
Route requests across multiple providers. Copy a provider slug to set your preference. Visit the docs for more info. Using a provider means you agree to their terms, listed under Legal.
| Provider |
|---|
| 203K | 9.4s | 42tps | $1.40/M | $4.40/M | Read:$0.26/M Write:— | — | — | 04/07/2026 | ||||
| 202K | 1.4s | 36tps | $1.40/M | $4.40/M | Read:$0.26/M Write:— | — | — | 04/07/2026 | ||||
| 203K | 2.1s | 28tps | $1.40/M | $4.40/M | Read:$0.26/M Write:— | — | — | 04/07/2026 | ||||
| 205K | 6.5s | 35tps | $1.40/M | $4.40/M | Read:$0.26/M Write:— | — | — | 04/07/2026 |
P50 throughput on live AI Gateway traffic, in tokens per second (TPS). Visit the docs for more info.
P50 time to first token (TTFT) on live AI Gateway traffic, in milliseconds. View the docs for more info.
Direct request success rate on AI Gateway and per-provider. Visit the docs for more info.
More models by Z.ai
| Model |
|---|
| 200K | 1.8s | 43tps | $1.20/M | $4.00/M | Read:$0.24/M Write:— | — | — |  | 04/01/2026 | ||||
| 203K | 1.0s | 24tps | $1.20/M | $4.00/M | Read:$0.24/M Write:— | — | — | | 03/15/2026 | ||||
| 203K | 0.4s | 66tps | $0.80/M | $2.56/M | Read:$0.16/M Write:— | — | — |    +3 | 02/12/2026 | ||||
| 205K | 0.1s | 840tps | $2.25/M | $2.75/M | Read:$2.25/M Write:— | — | — |  +2 | 12/22/2025 | ||||
| 205K | 0.5s | 103tps | $0.60/M | $2.20/M | Read:$0.11/M Write:— | — | — |   +1 | 09/30/2025 | ||||
| 200K | 0.1s | 133tps | $0.07/M | $0.40/M | Read:$0.01/M Write:— | — | — | |
About GLM 5.1
GLM 5.1 builds on the GLM-5 generation with a significant jump in coding capability, released April 7, 2026. Where GLM-5 introduced multiple thinking modes and agentic workflows, GLM 5.1 pushes the autonomy envelope: it sustains focus on one task for over eight hours, continuously planning, writing code, running tests, and improving its own output without human intervention.
The model targets long-horizon tasks that earlier models struggle with. Multi-file refactors, end-to-end feature implementation, and large-scale codebase migrations benefit from the extended autonomous execution window. Rather than handing back partial results for human review at each step, GLM 5.1 completes the full loop and delivers finished, tested code.
GLM 5.1 supports a context window of 204.8K tokens and max output of 202.8K tokens. Through AI Gateway, it shares the same unified API, built-in observability, and provider routing as other Z.ai models.
What To Consider When Choosing a Provider
- Configuration: GLM 5.1 excels when given a well-defined task with clear acceptance criteria. Provide a detailed specification, relevant file paths, and expected behavior so the model can plan its autonomous execution effectively.
- Configuration: Tasks running for hours consume tokens proportionally. Monitor usage through AI Gateway's observability tools and set budget limits for extended runs.
- Configuration: Despite autonomous self-correction, review the final output before merging into production. Treat GLM 5.1 as a thorough junior engineer who still needs a code review.
- Zero Data Retention: AI Gateway supports Zero Data Retention for this model via direct gateway requests (BYOK is not included). To configure this, check the documentation.
- Authentication: AI Gateway authenticates requests using an API key or OIDC token. You do not need to manage provider credentials directly.
When to Use GLM 5.1
Best For
- Large-scale refactors: Dozens of files where sustained context and iterative testing matter
- End-to-end feature implementation: Spec to tested, working code with minimal human checkpoints
- Codebase migrations: Hours of methodical file-by-file changes
- Complex bug investigations: The model autonomously traces root causes across a large codebase
- Autonomous coding agents: A model capable of multi-hour independent operation
Consider Alternatives When
- Short-horizon tasks: GLM-5 or GLM-5-Turbo handle coding tasks completing in minutes at lower cost
- Vision or multimodal input: GLM-5V-Turbo combines coding with screenshot and GUI understanding
- Interactive pair programming: GLM-4.7-Flash provides fast responses for real-time back-and-forth workflows
- Budget-constrained workloads: GLM-5-Turbo offers GLM-5-class capability at reduced per-token cost for shorter tasks
Conclusion
GLM 5.1 targets the gap between short-burst coding assistance and fully autonomous software engineering. For tasks that take hours of sustained, methodical work, it delivers complete results where shorter-context models would lose coherence or require repeated human intervention.
Frequently Asked Questions
How long can GLM 5.1 work on a single task?
Over eight hours of continuous autonomous operation. It plans, executes, tests, and iterates on its own output throughout that window.
How does GLM 5.1 differ from GLM-5?
GLM-5 introduced multiple thinking modes and agentic workflows for general-purpose reasoning. GLM 5.1 builds on that foundation with a specific focus on long-horizon coding tasks, sustaining autonomous operation for hours rather than minutes.
What is the context window for GLM 5.1?
204.8K tokens.
What is the pricing for GLM 5.1?
Check the pricing panel on this page for today's numbers. AI Gateway tracks rates across every provider that serves GLM 5.1.
How do I access GLM 5.1 through AI Gateway?
Use the
zai/glm-5.1model identifier with your AI Gateway API key. No separate Z.ai account is needed. BYOK is also supported.