Claude Sonnet 4.5 (2025-09-29) API
About
Build advanced reasoning agents with Claude Sonnet 4.5 (2025-09-29), a specialized AI model optimized for complex logic and chain-of-thought tasks. This model delivers cost-effective pricing at $3.00/1M input and $15.00/1M output tokens, native tool calling support. Access Claude Sonnet 4.5 (2025-09-29) via the LLM Gateway API with up to 64K output tokens.
Capabilities
Input Modalities
text
Output Modalities
text
Reasoning
Yes
Structured Output
Yes
Tool Use
Yes
WeightsClosed
Limits
Context Window
200K
Tokens
Input Limit
200K
Tokens
Max Output
64K
Tokens
Pricing
Standard (per 1M tokens)
Input
$3.00
Output
$15.00
Caching (per 1M tokens)
Read
$0.30
Frequently Asked Questions
Claude Sonnet 4.5 (2025-09-29) by LLM Gateway costs $3.00 per 1M input tokens and $15.00 per 1M output tokens. Cached reads cost $0.30 per 1M tokens.
Model Details
ID
claude-sonnet-4-5-20250929
Provider
LLM GatewayFamily
claude
Release Date
Sep 29, 2025
Knowledge Cutoff
N/A
API Integration
NPM Package
@ai-sdk/openai-compatible
Environment Variables
LLMGATEWAY_API_KEY
API Base URL
https://api.llmgateway.io/v1