# Anthropic Claude 1.0 — deprecation status

> Yes — Claude 1.0 is retired. Anthropic deprecated it on September 4, 2024 and shut it down on November 6, 2024; API requests to it now fail. The recommended replacement is Claude Haiku 4.5.

The first Claude released to developers, in March 2023, and the model that introduced Constitutional AI to a public API. It used the text-completion endpoint with literal "Human:" and "Assistant:" turn markers rather than a structured message list — a shape that reads as archaeology now.

## Facts

| Field | Value |
| --- | --- |
| Provider | Anthropic |
| Model id | `claude-1.0` |
| Status | Retired |
| Deprecated | September 4, 2024 |
| Shutdown | November 6, 2024 (631 days ago) |
| Last verified | July 30, 2026 |

## Replacement

- **Claude Haiku 4.5** (`claude-haiku-4-5-20251001`) · recommended — https://modeldeprecations.dev/anthropic/claude-haiku-4-5-20251001
  - Two generations and a whole API separate these. Claude 1 predates the Messages API, so a migration means moving off /v1/complete and its "\n\nHuman:"/"\n\nAssistant:" prompt format entirely.
  - Parameters it accepts: https://modelparams.dev/models/anthropic/claude-haiku-4-5-20251001

```diff
- "model": "claude-1.0"
+ "model": "claude-haiku-4-5-20251001"
```

## FAQ

### When did Anthropic Claude 1.0 shut down?

Anthropic Claude 1.0 shut down on November 6, 2024. API requests to it fail from that date onward.

### What replaces Anthropic Claude 1.0?

Anthropic recommends Claude Haiku 4.5 (`claude-haiku-4-5-20251001`) as the replacement for Anthropic Claude 1.0. Two generations and a whole API separate these. Claude 1 predates the Messages API, so a migration means moving off /v1/complete and its "\n\nHuman:"/"\n\nAssistant:" prompt format entirely.

### Is Anthropic Claude 1.0 still available?

No. Anthropic Claude 1.0 is retired and no longer served — it was shut down on November 6, 2024. Calls to it return an error.

### How do I migrate from Anthropic Claude 1.0 to claude-haiku-4-5-20251001?

Swap the model id in your API call: replace "claude-1.0" with "claude-haiku-4-5-20251001". Two generations and a whole API separate these. Claude 1 predates the Messages API, so a migration means moving off /v1/complete and its "\n\nHuman:"/"\n\nAssistant:" prompt format entirely.

## Sources

- [Anthropic model deprecations](https://platform.claude.com/docs/en/about-claude/model-deprecations) — accessed 2026-07-30

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Canonical page: https://modeldeprecations.dev/anthropic/claude-1.0
JSON: https://modeldeprecations.dev/api/v1/models/anthropic/claude-1.0.json