Claude Haiku 5.5

Anthropic · Haiku

Anthropic released Claude Haiku 5.5 on October 7, 2026.

Claude Haiku 5.5 is the Anthropic model launched on October 7, 2026, described as its most capable model tuned for high-volume and latency-sensitive work such as classification, routing, extraction and sub-agent tasks. It has a 1M token context window, 128k max output tokens and adaptive thinking with the effort parameter. It is available on the Claude API, Amazon Bedrock, Claude Platform on AWS, Google Cloud and Microsoft Foundry. It adds the browser use tool on the Claude API and Google Cloud, lowers the minimum cacheable prompt to 512 tokens, and runs safety classifiers that can decline a request.

Claude Haiku 5.5 at a glance

Released
API model id
claude-haiku-5-5
Available on
Claude APIAmazon BedrockClaude Platform on AWSGoogle CloudMicrosoft Foundry
Previous model
Claude Haiku 4.5 (October 15, 2025)
Announcement
platform.claude.com

What changed from Claude Haiku 4.5

Compared with Claude Haiku 4.5, the context window grows from 200k to 1M tokens and the output limit from 64k to 128k, and prompts as short as 512 tokens can be cached (down from 4,096).

Code written for Haiku 4.5 can break: manual extended thinking, sampling parameters, assistant prefill and the computer_20250124 tool can each return an error. A newer tokenizer counts the same text as about 30% more tokens.

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

Claude Haiku 5.5 release timeline

The launch and every later Anthropic release that mentions Claude Haiku 5.5, oldest first.

  • Launch of Claude Haiku 5.5

    We've launched Claude Haiku 5.5 ( claude-haiku-5-5 ), our most capable model tuned for high-volume and latency-sensitive work. It has a 1M token context window, 128k max output tokens, and adaptive thinking with the effort parameter. It's available on the Claude API, Claude in A…

    Source: Claude Platform Release Notes

Claude Haiku 5.5 FAQ

When was Claude Haiku 5.5 released?

Anthropic released Claude Haiku 5.5 on October 7, 2026. The launch entry below links to the official announcement.

Where is Claude Haiku 5.5 available?

Claude Haiku 5.5 is available on Claude API, Amazon Bedrock, Claude Platform on AWS, Google Cloud and Microsoft Foundry. Later availability changes are listed under follow-up releases on this page.

What is the Claude Haiku 5.5 API model id?

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

What came before Claude Haiku 5.5?

Claude Haiku 5.5 follows Claude Haiku 4.5, released on October 15, 2025.

Other Anthropic models

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