Technology & AI Research Desk | April 2026 | 5 min read
| ⚡ QUICK TAKEAWAYS
• Z.ai has released GLM-5.1 under an MIT open-source license — a 754B-parameter Mixture-of-Experts model designed for long-horizon autonomous tasks. • The model can operate on a single task for up to 8 hours, executing up to 1,700 steps — far beyond the ~20 steps of earlier agent systems. • It scores 58.4 on SWE-Bench Pro, outperforming GPT-5.4 and Claude Opus 4.6, while priced at $5.80 per million tokens combined. • API pricing is $1.40 per million input and $4.40 per million output tokens — significantly cheaper than frontier closed models. • A subscription Coding Plan is available at $27, $81 or $216 per quarter for developers who prefer flat-rate access. |
Z.ai has released GLM-5.1 — a massive 754-billion-parameter open-source model that marks a fundamental shift in AI agent design. While most AI models are optimised for fast, short responses, GLM-5.1 is built for sustained autonomous task execution over hours, not seconds. The release positions Z.ai as a serious competitor to closed frontier models from OpenAI, Google and Anthropic.
GLM-5.1 — KEY TECHNICAL NUMBERS
| 754B
Parameters Mixture-of-Experts architecture |
8 Hours
Max Task Duration Up to 1,700 steps per task |
202K tokens
Context Window 202,752-token context length |
What Makes GLM-5.1 Different: The 8-Hour Agent
Most AI language models are designed for rapid, single-turn exchanges — answer a question, generate some code, summarise a document. GLM-5.1 is designed around a fundamentally different use case: sustained autonomous task execution over extended periods. The model can operate continuously on a single complex task for up to eight hours, executing up to 1,700 steps and making thousands of tool calls without losing goal alignment.
Earlier agent-based systems could typically manage around 20 steps before performance degraded or goal drift occurred. The leap to 1,700 steps represents an order-of-magnitude improvement in autonomous capability. This is enabled by a 202,752-token context window and a ‘staircase’ optimisation pattern — where the model alternates between incremental improvements and structural strategy changes to avoid getting stuck in local optima during long tasks.
| PRACTICAL EXAMPLE — 8 Hours of Work
In testing, GLM-5.1 built a complete Linux-style desktop environment within eight hours of autonomous operation. A separate developer reported reducing a workflow that previously took one week down to two days. These are not marginal improvements — they represent a step-change in what AI agents can accomplish without human intervention during a task. |
Benchmark Performance: Beating GPT-5.4 at a Fraction of the Cost
GLM-5.1’s benchmark results are notable both in absolute terms and relative to its pricing:
| Benchmark | Score / Result | Context |
| SWE-Bench Pro | 58.4 | Outperforms GPT-5.4 and Claude Opus 4.6 |
| AIME 2026 (Math) | 95.3 | Advanced mathematics reasoning benchmark |
| GPQA-Diamond | 86.2 | Scientific reasoning benchmark |
| VectorDB Optimize | 655 iterations / 6,000+ tool calls | Improved QPS from 3,547 to 21,500 |
| KernelBench L3 | 3.6x speedup | Geometric mean across 50 ML tasks |
The SWE-Bench Pro score of 58.4 is particularly significant — it places GLM-5.1 above both GPT-5.4 and Claude Opus 4.6 on a widely used software engineering evaluation benchmark, while the model’s API pricing of $5.80 per million tokens combined is a fraction of GPT-5.4’s $17.50 or Claude Opus 4.6’s $30.00.
Pricing: API Rates and Subscription Plans
GLM-5.1 is positioned as a developer tool rather than a consumer product. The API pricing reflects competitive positioning against both open and closed alternatives:
| Model | Input /M | Output /M | Total /M | Notes |
| Grok 4.1 Fast | $0.20 | $0.50 | $0.70 | — |
| MiniMax M2.7 | $0.30 | $1.20 | $1.50 | — |
| Gemini 3 Flash | $0.50 | $3.00 | $3.50 | — |
| Kimi-K2.5 | $0.60 | $3.00 | $3.60 | — |
| MiMo-V2-Pro | $1.00 | $3.00 | $4.00 | — |
| GLM-5 | $1.00 | $3.20 | $4.20 | — |
| GLM-5-Turbo | $1.20 | $4.00 | $5.20 | — |
| GLM-5.1 (this model) | $1.40 | $4.40 | $5.80 | Open-source (MIT) |
| Claude Haiku 4.5 | $1.00 | $5.00 | $6.00 | — |
| Qwen3-Max | $1.20 | $6.00 | $7.20 | — |
| Gemini 3 Pro | $2.00 | $12.00 | $14.00 | — |
| GPT-5.2 | $1.75 | $14.00 | $15.75 | — |
| GPT-5.4 | $2.50 | $15.00 | $17.50 | — |
| Claude Sonnet 4.5 | $3.00 | $15.00 | $18.00 | — |
| Claude Opus 4.6 | $5.00 | $25.00 | $30.00 | — |
| GPT-5.4 Pro | $30.00 | $180.00 | $210.00 | — |
For developers who prefer subscription-based access, Z.ai offers a Coding Plan with three tiers:
| Plan | Price | Target Use |
| Lite | $27 / quarter | Entry-level developer access |
| Pro | $81 / quarter | Professional development usage |
| Max | $216 / quarter | Maximum access and throughput |
| OPEN-SOURCE STRATEGY — MIT LICENSE
GLM-5.1 is released under the MIT license — one of the most permissive open-source licences available. This means enterprises can download, modify and deploy the model commercially without royalties or usage restrictions. Z.ai, listed on the Hong Kong Stock Exchange at a $52.83 billion market valuation, is using open-source as a market expansion tool while keeping its performance-optimised proprietary model (GLM-5 Turbo) closed. |
Developer Integration and Known Limitations
GLM-5.1 integrates with major developer tools including Claude Code, OpenCode and Kilo Code, enabling adoption in existing software development workflows without major infrastructure changes. Early user feedback highlights improved reliability and task completion rates for complex, multi-step projects.
Z.ai acknowledges that challenges remain. Maintaining coherence over very long workflows and improving self-evaluation mechanisms for tasks without clear performance metrics are identified as active areas of development. The model’s performance on tasks with ambiguous success criteria is still evolving.
Key Takeaways
- GLM-5.1 is a 754B-parameter MIT-licensed open-source AI agent released by Z.ai — free to use commercially.
- It can autonomously execute tasks for up to 8 hours with up to 1,700 steps — a major leap from earlier 20-step agents.
- Scores 58.4 on SWE-Bench Pro — outperforming GPT-5.4 and Claude Opus 4.6 at $5.80/million tokens combined.
- API pricing: $1.40 input / $4.40 output per million tokens — significantly cheaper than frontier closed models.
- Subscription plans available from $27/quarter — integrates with Claude Code, OpenCode and Kilo Code.
- ai is publicly listed in Hong Kong at a $52.83 billion market cap, using open-source as a global expansion strategy.
DISCLAIMER: All specifications, benchmarks and pricing are based on official Z.ai announcements and publicly available data. Benchmark results may vary in real-world conditions. This content is intended for general informational purposes only.
