Claude Sonnet 4.5 API — pricing & specs
Claude Sonnet 4.5 is Anthropic's balanced mid-tier Claude, a text-only model for reasoning, coding, and everyday agentic tasks. An earlier pinned-stable snapshot preceding Sonnet 4.6, it suits reproducible deployments and sits between the lightweight Haiku and most-capable Opus tiers. On KeepRouter, Claude Sonnet 4.5 costs $3 per 1M input tokens and $15 per 1M output tokens, billed at cost with no markup and no monthly fee. Call it through the OpenAI- or Anthropic-compatible API with the model id claude-sonnet-4.5.
| Maker | Anthropic |
|---|---|
| Modality | Text |
| Pricing | $3 per 1M input tokens and $15 per 1M output tokens |
Frequently asked questions
How much does Claude Sonnet 4.5 cost on KeepRouter?
Claude Sonnet 4.5 is $3 per 1M input tokens and $15 per 1M output tokens, billed at cost with no markup and no monthly fee.
Who makes Claude Sonnet 4.5?
Claude Sonnet 4.5 is made by Anthropic. KeepRouter provides it through one OpenAI- and Anthropic-compatible API.
How do I call Claude Sonnet 4.5 via API?
Point your OpenAI- or Anthropic-compatible client at KeepRouter and set the model to "claude-sonnet-4.5". No provider-specific SDK needed.