GLM-5.1 API
About
Build advanced reasoning agents with GLM-5.1, a specialized AI model optimized for complex logic and chain-of-thought tasks. This model delivers cost-effective pricing at $1.40/1M input and $4.40/1M output tokens, native tool calling support, open weights architecture. Access GLM-5.1 via the Z.AI API with up to 131K output tokens.
Capabilities
Input Modalities
text
Output Modalities
text
Reasoning
Yes
Structured Output
Yes
Tool Use
Yes
WeightsOpen
Temperature
Adjustable
Attachment
Not Supported
Limits
Context Window
200K
Tokens
Input Limit
200K
Tokens
Max Output
131K
Tokens
Pricing
Standard (per 1M tokens)
Input
$1.40
Output
$4.40
Caching (per 1M tokens)
Read
$0.26
Write
Free
Frequently Asked Questions
GLM-5.1 by Z.AI costs $1.40 per 1M input tokens and $4.40 per 1M output tokens. Cached reads cost $0.26 per 1M tokens. Cache writes cost Free per 1M tokens.
Model Details
API Integration
NPM Package
@ai-sdk/openai-compatible
Environment Variables
ZHIPU_API_KEY
API Base URL
https://api.z.ai/api/paas/v4