Claude
Also known as Claude.ai
Anthropic's series of proprietary large language models, its flagship product.
At a glance
Release history
Claude and Claude Instant, Claude 2, Claude 3 Opus, Sonnet, Haiku …
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Anthropic and Claude Code
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Also on this page: Key facts · Links · Sources · Related pages
- Claude is a series of proprietary large language models made by Anthropic.
- It is fine-tuned with constitutional AI, training the model to follow a set of principles called a constitution.
- It comes in tiers including Opus, Sonnet and Haiku, released through 2026.
- It is available via a web interface, an API, mobile and desktop apps, and cloud platforms including Amazon Bedrock and Google Cloud Vertex AI.
Why it matters
- For anyone following AI assistants and agents, Claude is one of the most widely used model families and the product at the center of Anthropic's safety-focused strategy.
Key facts
- Maker
- Anthropic1
- First released
- 2023-031
- Tiers
- Fable, Opus, Sonnet, Haiku1
- Fine-tuning technique
- Constitutional AI1
- Agent harnesses
- Claude Code, Cowork, Design, Science1
Release history
The line under a date fills as it gets older: empty when new, full at 2 years.
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Claude and Claude Instant1
First two versions, limited to Anthropic-approved users.
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Claude 21
First version launched to the public.
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Claude 3 Opus, Sonnet, Haiku1
Three models in decreasing order of performance.
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Claude 3.5 Sonnet1
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Claude 4 Opus and Sonnet1
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Claude Opus 4.61
Followed by Sonnet 4.6 the same month.
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Claude Mythos1
Announced as Anthropic's most advanced model, not planned for public release.
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Claude Opus 5.51
Said to be comparable to Fable 5.1 while costing 40% less.
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Claude Sonnet 5.51
Said to cost half as much as Opus 5.5.
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Claude Haiku 5.53
Fast small model for summarization, subagents and browser use.
Connections
Links
Sources
Last checked against its sources today
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