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Claude Opus 4.5
Anthropic · Opus
Anthropic released Claude Opus 4.5 on November 24, 2025.
Claude Opus 4.5 is the Anthropic model launched on November 24, 2025, described at launch as its most intelligent model, combining maximum capability with practical performance. Anthropic aimed it at complex specialized tasks, professional software engineering and advanced agents, with step-change improvements in vision, coding and computer use. It launched at a lower price than previous Opus models; when Claude Opus 3 was retired in January 2026, Anthropic said Opus 4.5 offers significantly improved intelligence at a third of the cost. The effort parameter launched alongside it in public beta, and structured outputs came out of beta for it in January 2026.
Claude Opus 4.5 at a glance
- Released
- API model id
claude-opus-4-5- Available on
- Claude API
- Announcement
- anthropic.com
What changed
Opus 4.5 cut the price of Opus-class models (a third of Claude Opus 3's cost, according to Anthropic) and introduced the effort parameter, which lets developers trade response thoroughness for token efficiency.
Anthropic highlighted step-change gains in vision, coding and computer use over earlier Opus models.
New to model names and version numbers? Read how AI labs version their models.
Claude Opus 4.5 release timeline
The launch and every later Anthropic release that mentions Claude Opus 4.5, oldest first.
- Introducing Claude Opus 4.5
Our newest model, Claude Opus 4.5, is available today. It’s intelligent, efficient, and the best model in the world for coding, agents, and computer use.
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 - Models API adds line field for model grouping
We've added a line field to the Models API. GET /v1/models and GET /v1/models/{model_id} now return the model line each model belongs to. Claude Opus 4.5 and Claude Opus 4.6 both report opus, for example. Use line to group models without parsing their IDs. line is null for a mod…
Source: Claude Platform Release Notes
Claude Opus 4.5 FAQ
When was Claude Opus 4.5 released?
Anthropic released Claude Opus 4.5 on November 24, 2025. The launch entry below links to the official announcement.
Where is Claude Opus 4.5 available?
Claude Opus 4.5 is available on Claude API. Later availability changes are listed under follow-up releases on this page.
What is the Claude Opus 4.5 API model id?
Use claude-opus-4-5 in Anthropic's API.
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