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Claude Opus 5.5
Anthropic · Opus
Anthropic released Claude Opus 5.5 on September 22, 2026.
Claude Opus 5.5 is the Anthropic model launched on September 22, 2026 for long-running agentic coding and knowledge work. It has a 1M token context window by default, 128k max output tokens and always-on adaptive thinking, at $4 / $20 per million input / output tokens, cheaper than Claude Opus 5 at $5 / $25. It is available on the Claude API, Amazon Bedrock, Claude Platform on AWS, Google Cloud and Microsoft Foundry. Anthropic reports gains in agentic coding and code review, knowledge work, visual inputs and computer use. Fast mode launched in research preview on the Claude API and came out of research preview on October 15, 2026.
Claude Opus 5.5 at a glance
- Released
- API model id
claude-opus-5-5- Available on
- Claude APIAmazon BedrockClaude Platform on AWSGoogle CloudMicrosoft Foundry
- Previous model
- Claude Opus 5 (July 24, 2026)
- Announcement
- platform.claude.com
What changed from Claude Opus 5
Opus 5.5 is cheaper than Claude Opus 5 and thinks more per turn at a given effort level. Thinking can no longer be disabled: sending thinking disabled or a manual budget returns an error, and depth is set with effort, which defaults to medium.
Forced tool use returns an error, computer use requires the newer computer_toolset_20260801 on the Claude API and Google Cloud, and text between tool calls now comes back in thinking blocks.
New to model names and version numbers? Read how AI labs version their models.
Claude Opus 5.5 release timeline
The launch and every later Anthropic release that mentions Claude Opus 5.5, oldest first.
- Claude Opus 5.5 Launch
Launch of Claude Opus 5.5 (claude-opus-5-5) for long-running agentic coding and knowledge work. Features 1M token context window, 128k max output tokens, and adaptive thinking. Available on multiple platforms.
Source: Claude Platform Release Notes - Claude Sonnet 5.5 launch
Launched Claude Sonnet 5.5, a faster, lower-cost complement to Claude Opus 5.5 in the Claude 5.5 family.
Source: Claude Help Center Release Notes - Dreams research preview expanded
Dreams (research preview) now supports Claude Opus 5.5, Claude Fable 5.1, and Claude Sonnet 5.5.
Source: Claude Platform Release Notes - Fast Mode Availability for Claude Opus 5.5
Fast mode exits research preview for Claude Opus 5.5. No longer requires fast-mode-2026-02-01 beta header. Default fast mode rate limits added to all usage tiers.
Source: Claude Platform Release Notes - Fast Mode on Microsoft Foundry
Fast mode for Claude Opus 5.5 now available on Claude in Microsoft Foundry for Azure deployments.
Source: Claude Platform Release Notes - Claude Models on Google Cloud (Anthropic managed) launched
Launched Claude Models on Google Cloud (Anthropic managed), with Google Cloud IAM access control and billing through Google Cloud Marketplace. Fast mode available for Claude Opus 5.5.
Source: Claude Platform Release Notes
Claude Opus 5.5 FAQ
When was Claude Opus 5.5 released?
Anthropic released Claude Opus 5.5 on September 22, 2026. The launch entry below links to the official announcement.
Where is Claude Opus 5.5 available?
Claude Opus 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 Opus 5.5 API model id?
Use claude-opus-5-5 in Anthropic's API.
What came before Claude Opus 5.5?
Claude Opus 5.5 follows Claude Opus 5, released on July 24, 2026.
Other Anthropic models
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