Claude Haiku 4.5

Anthropic · Haiku

Anthropic released Claude Haiku 4.5 on October 15, 2025.

Claude Haiku 4.5 is Anthropic's small, fast model, launched on October 15, 2025 as its fastest and most intelligent Haiku model so far, with what Anthropic called near-frontier performance. It is aimed at real-time applications, high-volume processing and cost-sensitive deployments that still need strong reasoning. It has a 200k token context window and up to 64k output tokens. Structured outputs came out of beta for Haiku 4.5 on the Claude API in January 2026, and from April 2026 it was available self-serve to all Amazon Bedrock customers. Its successor is Claude Haiku 5.5.

Claude Haiku 4.5 at a glance

Released
API model id
claude-haiku-4-5
Available on
Claude APIAmazon Bedrock
Announcement
anthropic.com

What changed

Haiku 4.5 brought the Haiku line much closer to Anthropic's larger models: Anthropic positioned it as near-frontier performance at Haiku speed and cost, for work such as real-time chat, sub-agents and bulk processing.

New to model names and version numbers? Read how AI labs version their models.

Claude Haiku 4.5 release timeline

The launch and every later Anthropic release that mentions Claude Haiku 4.5, oldest first.

  • Introducing Claude Haiku 4.5

    Claude Haiku 4.5, our latest small model, is available today to all users. It offers similar coding performance to Claude Sonnet 4 at one-third the cost and more than twice the speed, with improved responsiveness for AI-assisted development workflows.

    Source: Anthropic
  • Structured outputs generally available

    Anthropic made structured outputs generally available on the Claude API for Sonnet 4.5, Opus 4.5, and Haiku 4.5. The update expanded schema support, reduced compilation latency, and removed the beta-header requirement.

    Source: Claude Platform Release Notes

Claude Haiku 4.5 FAQ

When was Claude Haiku 4.5 released?

Anthropic released Claude Haiku 4.5 on October 15, 2025. The launch entry below links to the official announcement.

Where is Claude Haiku 4.5 available?

Claude Haiku 4.5 is available on Claude API and Amazon Bedrock. Later availability changes are listed under follow-up releases on this page.

What is the Claude Haiku 4.5 API model id?

Use claude-haiku-4-5 in Anthropic's API.

Other Anthropic models

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