Z.ai: GLM-5.3 · fastrouter

GLM-5.3 is Z.ai’s latest GLM-5-series flagship, a 743B-parameter text-only foundation model post-trained from GLM-5.2 for frontier-level coding, long-horizon agentic workflows, and defensive cybersecurity analysis. It inherits GLM-5’s 200K-token context window and up to 128K-token outputs, supports advanced reasoning and tool use, and is initially exposed through Z.ai’s coding plan and forthcoming API access.

Base model All models on this base All models of the provider to the provider

Input, $/1M $0.56

Output, $/1M $2.48

Cache read $0.12

Cache write —

Context 1 048 576

Max output 131 072

Accepts text

Last checked 04.11.2026 12:00:14 UTC

Source provider's page

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API

OpenAI-compatible API: the official OpenAI SDKs work with this base URL. Replace YOUR_API_KEY with your key from the provider.

API base URL	`https://go.fastrouter.ai/api/v1`
Endpoint	`https://go.fastrouter.ai/api/v1/chat/completions`
Model id	`z-ai/glm-5.3`

curl

curl https://go.fastrouter.ai/api/v1/chat/completions \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model": "z-ai/glm-5.3", "messages": [{"role": "user", "content": "Hello!"}], "max_tokens": 256}'

Python

import requests

r = requests.post(
    "https://go.fastrouter.ai/api/v1/chat/completions",
    headers={"Authorization": "Bearer YOUR_API_KEY"},
    json={
      "model": "z-ai/glm-5.3",
      "messages": [
        {
          "role": "user",
          "content": "Hello!"
        }
      ],
      "max_tokens": 256
    },
)
print(r.json())

JavaScript

const r = await fetch("https://go.fastrouter.ai/api/v1/chat/completions", {
  method: "POST",
  headers: {Authorization: "Bearer YOUR_API_KEY", "Content-Type": "application/json"},
  body: JSON.stringify({
    "model": "z-ai/glm-5.3",
    "messages": [
      {
        "role": "user",
        "content": "Hello!"
      }
    ],
    "max_tokens": 256
  }),
});
console.log(await r.json());

Request (JSON)

{
  "model": "z-ai/glm-5.3",
  "messages": [
    {
      "role": "user",
      "content": "Hello!"
    }
  ],
  "max_tokens": 256
}

Response (JSON)

{
  "id": "chatcmpl-...",
  "object": "chat.completion",
  "model": "z-ai/glm-5.3",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": "Hi! How can I help?"
      },
      "finish_reason": "stop"
    }
  ],
  "usage": {
    "prompt_tokens": 9,
    "completion_tokens": 12,
    "total_tokens": 21
  }
}

The address is taken from the provider's model list; check it against the provider's documentation.

Provider's API documentation

Source: AI Rate Card, https://airatecard.com/en/c/offer%3Afastrouter%7Cz-ai/glm-5.3, prices checked 2026-11-04; seller's page: https://fastrouter.ai/models/z-ai/glm-5.3

Technical details

ID: offer:fastrouter|z-ai/glm-5.3