GLM 5.1

zai/glm-5.1

A chat model with a 203K-token context window, at $1.47 per million input tokens and $4.62 per million output tokens.

Details

Maker: zai
Kind: Chat
Context window: 202,800 tokens
Max output: 64,000 tokens
Input: $1.47 per million tokens
Cached input: $0.273 per million tokens, 81% off
Cache write: Same as input
Output: $4.62 per million tokens
Capabilities: Reasoning, tool use
Takes: Text
Returns: Text
Zero data retention: Not on every provider
No training on requests: Not on every provider
Released: 2026-04-07
Newer model: zai/glm-5.3-flashxReleased later by the same maker, costs no more, and lists the same capabilities. Compare the two

Description

GLM-5.1 delivers a major leap in coding capability, with particularly significant gains in handling long-horizon tasks. Unlike previous models built around minute-level interactions, GLM-5.1 can work independently and continuously on a single task for more than 8 hours—autonomously planning, executing, and improving itself throughout the process—ultimately delivering complete, engineering-grade results.

Call it

curl

curl https://phantom.codes/v1/chat/completions \
  -H "Authorization: Bearer $PHANTOM_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "zai/glm-5.1",
    "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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