Z.ai (Zhipu)

The GLM models with a permanent free tier.

Z.ai is Zhipu’s API, the lab behind GLM. The Flash line is the permanent free tier — glm-4.7-flash and glm-4.5-flash. GLM-5, GLM-5.2 and glm-4.7 bill per token. OpenAI-compatible at open.bigmodel.cn/api/paas/v4.

open.bigmodel.cn wants a Chinese phone number. The international portal at z.ai is email-only and a different account. Concurrency is per account and model, shown in the console. Flash chat goes to 200K.

Free models: 4
Max context: 200K
Free tier: GLM Flash models for free
Requirement: Phone verification, no card

Endpoint

Base URLhttps://open.bigmodel.cn/api/paas/v4

Env varZHIPU_API_KEY

Rate limitConcurrency set per account in the console

OpenAI-compatible
text
image
video
reasoning

Code examples

npm install openai

import OpenAI from 'openai'

const client = new OpenAI({
  baseURL: 'https://open.bigmodel.cn/api/paas/v4',
  apiKey: process.env.ZHIPU_API_KEY
})

const response = await client.chat.completions.create({
  model: 'glm-4.7-flash',
  messages: [{ role: 'user', content: 'Explain closures in one paragraph.' }]
})

console.log(response.choices[0].message.content)

pip install openai

import os
from openai import OpenAI

client = OpenAI(
    base_url="https://open.bigmodel.cn/api/paas/v4",
    api_key=os.environ["ZHIPU_API_KEY"],
)

response = client.chat.completions.create(
    model="glm-4.7-flash",
    messages=[{"role": "user", "content": "Explain closures in one paragraph."}],
)

print(response.choices[0].message.content)

curl https://open.bigmodel.cn/api/paas/v4/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $ZHIPU_API_KEY" \
  -d '{
    "model": "glm-4.7-flash",
    "messages": [{"role": "user", "content": "Explain closures in one paragraph."}]
  }'

Worth knowing

The Flash models are the free ones (glm-4.7-flash, glm-4.5-flash). glm-4.7, glm-5 and glm-5.2 bill per token.
open.bigmodel.cn wants a Chinese phone number. The international portal at z.ai is email-only.

Models you get for free4

GLM 4.7 Flashglm-4.7-flash
GLM 4.5 Flashglm-4.5-flash
GLM 4.6 Flashglm-4.6-flash
GLM 4 Flashglm-4-flash