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Claude Opus 4.8
Anthropic · Opus
Anthropic released Claude Opus 4.8 on May 28, 2026.
Claude Opus 4.8 is the Anthropic model launched on May 28, 2026 as its most capable model at the time. It supports a 1M token context window by default on the Claude API, Amazon Bedrock, Google Cloud and Microsoft Foundry, 128k max output tokens, and the same tools and platform features as Claude Opus 4.7. It launched with mid-conversation system messages, which let instructions change during a long session without losing prompt cache hits. Effort defaults to high, adaptive thinking triggers reasoning only when a turn needs it, and the minimum cacheable prompt is 1,024 tokens. Fast mode is available as a research preview on the Claude API, and became the default for Max plan users in Claude Code.
Claude Opus 4.8 at a glance
- Released
- API model id
claude-opus-4-8- Available on
- Claude APIAmazon BedrockGoogle CloudMicrosoft Foundry
- Previous model
- Claude Opus 4.7 (April 16, 2026)
- Announcement
- platform.claude.com
What changed from Claude Opus 4.7
Compared with Claude Opus 4.7, Opus 4.8 makes the 1M token context window the default, lowers the minimum cacheable prompt length to 1,024 tokens, and wastes fewer thinking tokens at the same effort level because adaptive thinking only reasons when a turn needs it.
Sampling parameters still return an error at non-default values, as on Opus 4.7.
New to model names and version numbers? Read how AI labs version their models.
Claude Opus 4.8 release timeline
The launch and every later Anthropic release that mentions Claude Opus 4.8, oldest first.
- Claude Opus 4.8 launch
Claude Opus 4.8 upgrade with improvements in coding, agentic skills, and practical knowledge work
Source: Claude Help Center Release Notes
Claude Opus 4.8 FAQ
When was Claude Opus 4.8 released?
Anthropic released Claude Opus 4.8 on May 28, 2026. The launch entry below links to the official announcement.
Where is Claude Opus 4.8 available?
Claude Opus 4.8 is available on Claude API, Amazon Bedrock, Google Cloud and Microsoft Foundry. Later availability changes are listed under follow-up releases on this page.
What is the Claude Opus 4.8 API model id?
Use claude-opus-4-8 in Anthropic's API.
What came before Claude Opus 4.8?
Claude Opus 4.8 follows Claude Opus 4.7, released on April 16, 2026.
Other Anthropic models
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