GLM 5.3 API

About GLM 5.3

Coding and agentic model with a 1M token context, 128K output, always-on reasoning at low, high, or max effort, native web search, and tool calling.

Notes: - Context window: 1M tokens - Maximum output: 128K tokens - Always reasons; thinking cannot be disabled - Reasoning effort: low, high, or max (max recommended for complex coding) - A request for a different effort, or to turn thinking off, is served at the nearest supported level - Built-in web search adds $0.033 per request when used - Supports function calling, structured output (JSON mode), and streaming

Also known as Z.ai GLM 5.3

GLM 5.3 specs

Model ID

glm-5-3

Provider

Z.ai

Category

Text Generation

Released

Aug 14, 2026

Context window

1M tokens

Max output

131,072 tokens

Input

Text

Output

Text

Structured output

JSON Mode

Region

Singapore

Endpoints

POST/v1/chat/completionsPOST/v1/responsesPOST/v1/messagesPOST/v1beta/models/glm-5-3:generateContent

Alternate model IDs

glm-5.3zai/glm-5.3zhipu/glm-5.3

GLM 5.3 API pricing

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 5.3 API

GLM 5.3 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-5-3. 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-5-3",
    "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-5-3",
    messages=[{"role": "user", "content": "Write a haiku about the ocean."}],
)
print(response.choices[0].message.content)

GLM 5.3 API parameters

Request parameters supported by the GLM 5.3 API on EmpirioLabs. Defaults apply when a field is omitted.

GLM 5.3 API: common questions

How much does the GLM 5.3 API cost?

On EmpirioLabs, GLM 5.3 is billed pay as you go: Input $1.40 per 1M prompt tokens; Output $4.40 per 1M generated tokens; Web search $0.033 per request. The live rate card on this page always matches what the API charges.

What is the context window of GLM 5.3?

GLM 5.3 supports a 1M-token context window with up to 131,072 output tokens per response.

Is the GLM 5.3 API OpenAI-compatible?

Yes. GLM 5.3 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-5-3.

Can I try GLM 5.3 in the browser before integrating?

Yes. The EmpirioLabs playground runs GLM 5.3 in the browser with the same parameters the API exposes, so you can test prompts before writing code.

How do I get a GLM 5.3 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.