GLM 5.1
VerifiedGLM 5.1 handles extended text contexts up to 200k tokens for complex tasks.
About GLM 5.1
GLM 5.1 uses a transformer design scaled for very long input sequences. Z.AI maintains full control over the weights and releases updates through managed channels. This closed approach prioritizes stability and security for enterprise users.
Its primary strength lies in retaining coherence across documents or conversations that exceed typical context limits. The model processes raw text without additional modalities, keeping output focused and consistent.
Typical usage includes legal document review, technical report summarization, and multi-turn dialogue systems. Developers integrate it via API for applications that demand reliable handling of large textual datasets.
Capabilities
How GLM 5.1 compares
GLM 5.1 (striped bar) vs other language models on intelligence, speed and price.
Price
USD per 1M output tokens · Lower is better · GLM 5.1 ranks #82 of 95
Sources: Artificial Analysis (intelligence, speed) · OpenRouter (price).
Best for
Long Document Analysis
GLM 5.1 processes entire books, research papers, or legal contracts within its context window to extract insights and generate summaries.
Large Codebase Review
The model maintains coherence across extensive code repositories to identify bugs, suggest refactors, and explain architecture.
Extended Conversation History
It sustains detailed multi-turn dialogues or role-play scenarios that reference earlier exchanges without losing context.
Strengths & limitations
Strengths
- +Very large context window for processing lengthy inputs
- +Strong multilingual capabilities especially Chinese-English
- +Versatile across general reasoning and coding tasks
Limitations
- –Text-only modality with no vision support
- –High compute requirements for maximum context length
- –Standard LLM risks of hallucination on complex topics
Pricing by provider
Live per-provider pricing & uptime, routed via OpenRouter. Prices are USD per 1M tokens.
| Provider | Input /1M | Output /1M | Context | Uptime |
|---|---|---|---|---|
| GMICloud(fp8) | $0.98 | $3.08 | 203K | 43.0% |
| Baidu(fp8) | $0.98 | $3.08 | 203K | 100.0% |
| Wafer(fp4) | $1.00 | $3.20 | 203K | 99.8% |
| DeepInfra(fp4) | $1.05 | $3.50 | 203K | 100.0% |
| StreamLake | $1.19 | $3.74 | 200K | 99.8% |
| Chutes(fp8) | $1.20 | $4.00 | 203K | 96.2% |
| Phala | $1.21 | $4.20 | 203K | 94.7% |
| AtlasCloud(fp8) | $1.26 | $3.96 | 203K | 100.0% |
| BaseTen(fp4) | $1.30 | $4.30 | 203K | 0.0% |
| Novita(fp8) | $1.38 | $4.40 | 205K | 99.7% |
| Together | $1.40 | $4.40 | 203K | 96.2% |
| Parasail(fp8) | $1.40 | $4.40 | 203K | 100.0% |
| Fireworks | $1.40 | $4.40 | 203K | 99.0% |
| Z.AI(fp8) | $1.40 | $4.40 | 203K | 100.0% |
| SiliconFlow(fp8) | $1.40 | $4.40 | 205K | 99.9% |
| Ambient(fp8) | $1.40 | $4.40 | 203K | 100.0% |
| Friendli | $1.40 | $4.40 | 203K | 100.0% |
| Inceptron(fp8) | $1.40 | $4.40 | 203K | 99.6% |
| Venice(fp8) | $1.75 | $5.50 | 200K | — |
Cost calculator
Estimate what GLM 5.1 would cost for your usage.
Based on GLM 5.1's $0.98/1M input · $3.08/1M output. Estimate only — actual cost varies by provider and caching.
Quick start
OpenRouter's API is OpenAI-compatible — most SDKs work by just swapping the base URL. Only the model slug changes between models.
import OpenAI from "openai";
const client = new OpenAI({
baseURL: "https://openrouter.ai/api/v1",
apiKey: process.env.OPENROUTER_API_KEY,
});
const completion = await client.chat.completions.create({
model: "z-ai/glm-5.1",
messages: [{ role: "user", content: "Hello!" }],
});
console.log(completion.choices[0].message.content);Model slug: z-ai/glm-5.1
Editor's verdict
GLM 5.1 is Z.AI's proprietary language models with a 203K-token context window.
At $3.08 per 1M output tokens, it is mid-priced for its class, served by 19 providers.
It is available through Z.AI's API and aggregators like OpenRouter.
Best suited to very large context window for processing lengthy inputs and strong multilingual capabilities especially chinese-english.
Frequently asked questions
The model provides a context window of 202752 tokens.
User reviews
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