GLM-5.1 is now prior-release context for the Z.AI coding lane. Use GLM-5.2 for the current 1M-context GLM coding model, pricing, and comparison guidance. This page remains useful for older GLM-5.1 references, existing integrations, and historical price/context comparisons.
Z.AI’s earlier GLM-5.1 docs list a 200K context window, 128K max output, $1.40 input / $4.40 output per 1M tokens, and a 58.4 SWE-Bench Pro claim. Current-facing GLM searches should go to GLM-5.2 because Z.AI now documents GLM-5.2 with 1M context and the same public API price anchor.
Best next click: GLM-5.2 guide. Coupon/referral searches should go to the Z.AI coupon guide.
Quick Facts
| Spec | GLM-5.1 |
|---|---|
| Provider | Z.AI |
| Input / output | Text / text |
| Context window | 200K tokens |
| Max output | 128K tokens |
| API pricing | $1.40 input / $4.40 output per 1M tokens |
| Coding plan | Starts at $18/month, supported-tools-only |
| Published coding benchmark | Z.AI-published SWE-Bench Pro 58.4 |
| Useful for | Supported-tool budget lane, long-horizon coding, agent workflows |
Model Comparison Snapshot
| Model | API input/output | Context | Coding signal | Best use |
|---|---|---|---|---|
| GLM-5.1 | $1.40 / $4.40 | 200K | Z.AI-published SWE-Bench Pro 58.4 | Low-cost coding-agent subscription lane |
| GLM-5.2 | $1.40 / $4.40 | 1M | Z.AI-published GLM-5.2 benchmark claims | Current GLM long-context coding lane |
| Kimi K2.6 | $0.95 / $4.00 | 256K | Strong open-weight coding/agent positioning | Kimi workflows, multimodal inputs, open-weight preference |
| GPT-5.5 | $5.00 / $30.00 | 1.05M | OpenAI’s frontier coding/pro model | OpenAI-native coding and professional work |
| Claude Opus 4.7 | $5.00 / $25.00 | 1M-class | Anthropic’s premium coding and agent model | Hardest coding, multi-step agents, highest-confidence work |
Do not over-read benchmark margins or vendor tables. Public benchmarks are shortlist signals, not purchase proof. Run the model on your own bug fixes, refactors, and test-generation tasks before moving work from GPT or Claude.
GLM-5.1 vs Current GLM, Kimi, OpenAI, And Anthropic
| Decision lane | GLM-5.1 / Z.AI | Kimi lane | OpenAI lane | Anthropic lane |
|---|---|---|---|---|
| Best fit | Cheap supported-tool coding subscription | API-heavy value workflows and Kimi-native tools | OpenAI-native products and broad API ecosystem | High-confidence coding review, architecture, and Claude Code-native work |
| Cost posture | Low-cost subscription plus low API price anchor | Usually value-focused API routing | Premium API spend for harder tasks | Premium subscription/API spend for harder tasks |
| Tool posture | Strong when you stay inside Z.AI-supported tools | Strong where your stack already supports Kimi | Strongest in OpenAI-native integrations | Strongest in Claude-native workflows |
| Risk | Supported-tool restrictions and quota multipliers | Provider/tool availability can shift | Cost can rise quickly in agent loops | Cost and policy constraints can shape third-party tool use |
| Practical role | Daily budget coding lane to test | Budget API lane or specialist agent lane | Premium fallback and final arbitration | Premium fallback, review, and complex refactor lane |
The important framing: GLM-5.1 is a prior value/coding-lane recommendation. For new GLM evals, test GLM-5.2 first, then keep GLM-5.1 only where existing tool routing still depends on it.
Why It Matters
Claude and GPT remain the premium lanes, but their API pricing turns multi-step coding agents into real spend. GLM-5.1 gives you a cheaper model to put behind supported coding tools while reserving Opus or GPT for the jobs where the extra cost is actually visible.
The practical pattern:
- Route routine development to GLM-4.7 or GLM-4.5-Air inside the Coding Plan.
- Escalate difficult planning, large refactors, and stuck bugs to GLM-5.1.
- Keep Claude Opus 4.7 or GPT-5.5 for critical tasks where failure costs more than the API bill.
Coding Plan Caveats
The Coding Plan is not a blanket unlimited API subscription. Z.AI says it is restricted to officially supported tools and products. The docs list 5-hour limits, weekly limits, and higher quota deductions for GLM-5.1 and GLM-5-Turbo during peak and off-peak periods.
Current plan models are:
| Model | Role |
|---|---|
| GLM-5.1 | Hard coding, long-horizon work, advanced planning |
| GLM-5-Turbo | Advanced-model lane with similar quota treatment |
| GLM-4.7 | Routine development and default daily coding |
| GLM-4.5-Air | Lightweight, lower-cost tasks |
Z.AI documents core coding-tool support for Claude Code, OpenCode, Cursor, Cline, TRAE, Qoder, Droid, Kilo Code, Roo Code, Crush, Goose, and Eigent. OpenClaw is documented separately as a supported general-agent path with secondary scheduling and best-effort delivery.
For most buyers, that means GLM-5.1 is best viewed as a budget coding lane, not a total replacement for every provider account.
Deployment Eval Plan
Do not buy on a benchmark headline alone. A useful first pass is:
| Test | What to ask GLM-5.1 to do | Pass signal |
|---|---|---|
| Bug fix | Fix a real failing test with local context | Small patch, correct diagnosis, no unrelated churn |
| Refactor | Move code across 2-4 files | Preserves behavior and follows project style |
| Review | Review a risky change before merge | Finds concrete issues without inventing policy |
| Long task | Run a multi-step cleanup through your coding tool | Maintains task state and uses tests instead of guessing |
If GLM-5.1 passes those tasks, it is a good candidate for the cheap daily lane. If it misses project-specific constraints, keep it as a secondary model and route harder work to your premium fallback.
When To Use GLM-5.1
Use it when:
- You want a cheap supported-tool coding workflow.
- You use Claude Code, OpenCode, Cursor, Cline, TRAE, Qoder, Droid, Kilo Code, Roo Code, Crush, Goose, Eigent, or the documented OpenClaw path.
- You are doing long coding loops where GPT-5.5 or Opus API costs would be hard to justify.
- Your evals show GLM-5.1 is good enough for your codebase.
Avoid it when:
- You need the strongest possible model for a high-risk change.
- You need unrestricted SDK/API usage under the subscription.
- You cannot tolerate weekly caps, 5-hour quotas, or peak-hour multipliers.
- You need the provider with the deepest enterprise compliance posture.
Related links
- /models/glm-5.2/ - Current GLM-5.2 1M-context coding model guide
- /tools/zai/ - Z.AI Coding Plan CTA, quotas, and referral disclosure
- /value/deals/zai-glm-coding-discount/ - Z.AI coupon, referral code, and GLM Coding discount answer
- /models/glm-4.7/ - Legacy GLM 4.7 context
- /value/smart-spend/ - Low-cost upgrade strategy
- /value/free-stack/ - Free paths before paying
- /compare/models/budget-tier/ - Budget model comparison
Sources
- Z.AI GLM-5.1 docs
- Z.AI pricing
- Z.AI GLM Coding Plan overview
- Z.AI supported tool integration
- Z.AI OpenClaw integration
- OpenAI GPT-5.5 model pricing
- Anthropic Claude Opus 4.7 pricing
- Kimi API platform pricing
Last verified: June 20, 2026. Pricing, model availability, supported tools, Coding Plan quota rules, and invite terms can change quickly.