Anthropic: Claude Sonnet 4.5 (20250929) API
About
Build advanced reasoning agents with Anthropic: Claude Sonnet 4.5 (20250929), 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 Anthropic: Claude Sonnet 4.5 (20250929) via the Helicone API with up to 64K output tokens.
Capabilities
Input Modalities
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Output Modalities
text
Reasoning
Yes
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
Write
$3.75
Frequently Asked Questions
Anthropic: Claude Sonnet 4.5 (20250929) by Helicone costs $3.00 per 1M input tokens and $15.00 per 1M output tokens. Cached reads cost $0.30 per 1M tokens. Cache writes cost $3.75 per 1M tokens.
Model Details
ID
claude-sonnet-4-5-20250929
Provider
HeliconeFamily
claude-sonnet
Release Date
Sep 29, 2025
Knowledge Cutoff
Sep 1, 2025
API Integration
NPM Package
@ai-sdk/openai-compatible
Environment Variables
HELICONE_API_KEY
API Base URL
https://ai-gateway.helicone.ai/v1