GLM 5.1 API

About GLM 5.1

Long-context Zhipu AI reasoning model with 202K context, 128K output, tool calling, structured output, and cache support.

Notes: - Served by Alibaba Cloud Model Studio in China deployment mode - Context window: 202K tokens - Maximum output: 128K tokens - Supports function calling, structured output, and context cache - Structured output should run with enable_thinking=false - Does not support web search, batches, prefix continuation, or fine-tuning

Also known as Z.ai GLM 5.1, GLM-5.1, glm-5-1

GLM 5.1 specs

Model ID

glm-5-1

Provider

Z.ai

Category

Text Generation

Released

Apr 7, 2026

Context window

202K tokens

Input

Text

Output

Text

Region

China

Endpoints

POST /v1/chat/completions
POST /v1/responses
POST /v1/messages

GLM 5.1 API pricingSave up to 41%

Live pay-as-you-go rates from the EmpirioLabs catalog. You are billed only for what you use, with no monthly minimum.

How to call the GLM 5.1 API

GLM 5.1 serves the OpenAI-compatible Chat Completions API. Point any OpenAI SDK at https://api.empiriolabs.ai/v1 with your EmpirioLabs API key and use the model id glm-5-1. Get an API key from the EmpirioLabs dashboard.

curl https://api.empiriolabs.ai/v1/chat/completions \
  -H "Authorization: Bearer $EMPIRIOLABS_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "glm-5-1",
    "messages": [
      {"role": "user", "content": "Write a haiku about the ocean."}
    ]
  }'

from openai import OpenAI

client = OpenAI(
    base_url="https://api.empiriolabs.ai/v1",
    api_key="YOUR_EMPIRIOLABS_API_KEY",
)

response = client.chat.completions.create(
    model="glm-5-1",
    messages=[{"role": "user", "content": "Write a haiku about the ocean."}],
)
print(response.choices[0].message.content)

GLM 5.1 API parameters

Request parameters supported by the GLM 5.1 API on EmpirioLabs. Defaults apply when a field is omitted.

GLM 5.1 API: common questions

How much does the GLM 5.1 API cost?

On EmpirioLabs, GLM 5.1 is billed pay as you go: Input <=32K $0.825 (was $1.40); 32K-200K $1.10 (was $1.40) per 1M prompt tokens; Output <=32K $3.301 (was $4.40); 32K-200K $3.851 (was $4.40) per 1M generated tokens; Implicit cache read <=32K $0.165 (was $0.26); 32K-200K $0.22 (was $0.26) per 1M cached input tokens. The live rate card on this page always matches what the API charges.

What is the context window of GLM 5.1?

GLM 5.1 supports a 202K-token context window.

Is the GLM 5.1 API OpenAI-compatible?

Yes. GLM 5.1 serves the OpenAI-compatible Chat Completions API, so existing OpenAI SDKs work by pointing base_url at https://api.empiriolabs.ai/v1 and setting the model id to glm-5-1.

Can I try GLM 5.1 in the browser before integrating?

Yes. The EmpirioLabs playground runs GLM 5.1 in the browser with the same parameters the API exposes, so you can test prompts before writing code.

How do I get a GLM 5.1 API key?

Create an EmpirioLabs account, then generate a key under API Keys in the dashboard. Billing is pay-as-you-go credits, so you only pay for the requests you make.