China AI Hub
API / zai
zai API
Provider: zhipu-ai · Type: official
zai is an API by zhipu-ai, served at https://api.z.ai/api/paas/v4/chat/completions for official models, exposing GLM-5.2, GLM-5.3-Flash, GLM-5.3.
| Key fact | Value |
|---|---|
| Endpoint | https://api.z.ai/api/paas/v4/chat/completions |
| Authentication | Bearer API key |
| Streaming | Yes |
| Function calling | Yes |
| Tool calling | Yes |
| Structured output | Unknown |
| Vision | Yes |
| Audio | Unknown |
| Regions | international, china |
| Cloud providers | Z.ai, BigModel |
| Documentation | https://docs.z.ai/ |
Context limits
| Model | Input limit | Output limit |
|---|---|---|
| glm-5.3 | 1,048,576 | 131,072 |
| glm-5.3-flash | 1,048,576 | 131,072 |
The Z.ai API (Zhipu’s international platform) serves the GLM family via an OpenAI-compatible Chat
Completions endpoint at https://api.z.ai/api/paas/v4/chat/completions. GLM-5.3 additionally supports
the OpenAI Responses protocol (base https://api.z.ai/api/v1) and the Anthropic Messages protocol (base
https://api.z.ai/api/anthropic); the GLM Coding Plan uses https://api.z.ai/api/coding/paas/v4.
Authentication is a Bearer API key. Streaming is supported, with tool_stream: true for tool-streaming
(recommended for Flash models). The China platform (BigModel, open.bigmodel.cn) is operated separately.
Sources
Data interpretation
| Field | Value | Evidence type |
|---|---|---|
| Endpoint | https://api.z.ai/api/paas/v4/chat/completions | Official |
| Authentication | Bearer API key | Official |
| Capabilities | Streaming, Function calling, Tool calling, Vision | Official |
| Models served | 3 models in the database | China AI Hub analysis |
Evidence types: Official = vendor documentation or official pages. China AI Hub analysis = derived from the database itself. See the sourcing policy.
What is the zai API endpoint?
The zai API endpoint is https://api.z.ai/api/paas/v4/chat/completions.
How do you authenticate with the zai API?
Bearer API key.
What are the context limits of the zai API?
glm-5.3: 1,048,576 in / 131,072 out; glm-5.3-flash: 1,048,576 in / 131,072 out.
Does the zai API support function calling?
Yes — the zai API supports function calling.
Where does China AI Hub get its zai API data?
From 2 sources, last verified 2026-09-20.