GLM 5.3 FlashX

zai/glm-5.3-flashx

A chat model with a 1M-token context window, at $0.3885 per million input tokens and $1.3125 per million output tokens.

Details

Maker: zai
Kind: Chat
Context window: 1,000,000 tokens
Max output: 131,072 tokens
Input: $0.3885 per million tokens
Cached input: $0.07875 per million tokens, 80% off
Cache write: Same as input
Output: $1.3125 per million tokens
Capabilities: Reasoning, tool use, vision
Takes: Text, image
Returns: Text
Zero data retention: Not on every provider
No training on requests: Not on every provider
Released: 2026-09-18

Description

GLM-5.3-FlashX is the high-speed serving option for Z.ai’s native multimodal coding model, featuring 320B total parameters, 18B activated parameters, and a 1M-token context window. Its efficient hybrid attention architecture supports visual coding, tool use, and end-to-end professional workflows across code, browsers, documents, and graphical interfaces.

Call it

curl

curl https://phantom.codes/v1/chat/completions \
  -H "Authorization: Bearer $PHANTOM_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "zai/glm-5.3-flashx",
    "messages": [
      {"role": "user", "content": "Hello"}
    ]
  }'

Set PHANTOM_KEY to your key. Any OpenAI client works with the base URL https://phantom.codes/v1.

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