Claude.ai
App surface by Anthropic · site · lifecycle docs
Claude.ai (officially “Claude”, formerly Chat) is a chatbot app by Anthropic released in 2023.
Since September 16, 2026, the app uses the Claude Code harness under-the-hood. This is distinct from the Claude Code product surface which has its own deprecation lifecycle. The two surfaces ship in the same web/mobile/desktop app.
Architecture
- Claude Code — agent harness and runtime
- System prompts
- Memory system prompt sections
- System reminders
Cowork
Claude Cowork was an agent product released January 12, 2026, marketed toward knowledge workers. It was available only as a GUI and was powered by Claude Code internally. Cowork also included the Dispatch feature, which allows an agent to work on users’ computers remotely with filesystem access.
On September 16, 2026, Anthropic merged it into Claude.ai, alongside releasing Claude Docs and Claude Slides and making Claude Design available inside conversations.1 The rollout began with Pro and Max plans on web, desktop and mobile; Team and Free were to follow, and Enterprise administrators were promised at least 30 days’ notice. Standalone Claude Design continued to operate separately.
Model availability
Claude models deployed to Claude.ai have a shorter lifespan than on the Claude Platform API.
Claude.ai model retirement dates aren’t consistently documented by Anthropic, unlike API deprecations. As such, the table below relies on historical screenshots of the model picker and browser probes we run periodically. You can help contribute to this reference by sending us model picker screenshots.
| Model | Launched | Retired |
|---|---|---|
| Opus 3 | 2024-03-04 | - |
| Sonnet 3 | 2024-03-04 | Between 2024-06 and 2024-112 |
| Haiku 3 | 2024-03-04 | Between 2024-10 and 2025-053 |
| Sonnet 3.5 | 2024-06-20 | Between 2024-11 and 2025-0523 |
| Haiku 3.5 | 2024-10-22 | Early 2026(?) |
| Sonnet 3.6 | 2024-10-22 | 2025-05-223 |
| Sonnet 3.7 | 2025-02-24 | Between May 2025 and Nov 202534 |
| Sonnet 4 | 2025-05-22 | Between Jan 2026 and Apr 202656 |
| Opus 4 | 2025-05-22 | 2026-01-167 |
| Opus 4.1 | 2025-08-05 | 2026-01-167 |
| Sonnet 4.5 | 2025-09-29 | 2026-05-27 or 2026-06-22(?)8 |
| Haiku 4.5 | 2025-10-15 | - |
| Opus 4.5 | 2025-11-24 | ~2026-049 |
| Opus 4.6 | 2026-02-05 | - |
| Sonnet 4.6 | 2026-02-17 | - |
| Opus 4.7 | 2026-05-28 | - |
| Opus 4.8 | 2026-05-28 | - |
| Fable 5 | 2026-06-09 | - |
| Sonnet 5 | 2026-06-30 | - |
| Opus 5 | 2026-07-24 | - |
| Fable 5.1 | 2026-09-01 | - |
This table is the source of record for Claude.ai model availability (there is no official changelog for it). Firm dates are mirrored into each model’s metadata as claude-dot-ai provider rows — which feed the infoboxes and the tables on model deprecations — while fuzzy ranges and conflicting sources stay here with their citations.
Every model shown above without a retirement date was present in the model picker on September 21, 2026.10 Opus 3 was offered under More models with the exact id claude-3-opus-20240229, and was absent from the picker on Claude Code at the same time on the same account.
Footnotes
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Claude Cowork and chat are now one Claude (Anthropic, Sep 16, 2026) ↩
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Nov 16, 2024 model picker with S3.6, S3.5, O3, H3 - @voooooogel via X ↩ ↩2
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May 22, 2025 model picker with O4, S4, S3.7, O3, H3.5 - @1thousandfaces_ via X, @dyot_meet_mat ↩ ↩2 ↩3 ↩4
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Nov 24, 2025 model picker with O4.5, S4.5, H4.5, O4.1, O4, S4, O3, H3.5 @__ghostfail via X (Nov 24, 2025) ↩
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Jan 17, 2026 model picker showing 4.5 models and O3, H3.5, S4 @repligate via X ↩
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Apr 8, 2026 remark about how Sonnet 4 was removed but safety classifiers can still trigger a fallback to it @voooooogel via X ↩
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Release notes (Claude Help Center, retrieved July 3, 2026) ↩ ↩2
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Sources conflict on the exact app removal date. I Asked Claude Sonnet 4.5 How It Felt About Being Retired (Angie D., generativeai.pub, May 2026) says it was originally slated for May 15, 2026, then actually removed May 27. But Claude Sonnet 4.5 Retires June 22: What to Do Now (Vantage Point, Jun 18, 2026) — published after the alleged May 27 removal — says removal from the picker was still upcoming on June 22. Both are consumer-app-only claims, not API. Unresolved. ↩
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@__ghostfail via X (Apr 16, 2026) ↩
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Model picker read from the DOM on both
claude.ai/newandclaude.ai/code, Sep 21, 2026, one Max account. Labels were checked against each entry’sdata-model-id. ↩