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Anthropic claude-3-sonnet-20240229

Claude Sonnet 3 (Anthropic)

Retired

Yes — Claude Sonnet 3 is retired. Anthropic deprecated it on January 21, 2025 and shut it down on July 21, 2025; API requests to it now fail. The recommended replacement is Claude Sonnet 4.6.

The middle model of the original Claude 3 family, positioned between Haiku and Opus on the price ladder that every provider has copied since. Retired July 2025.

The facts

Provider Anthropic
Model id claude-3-sonnet-20240229
Released February 29, 2024
Deprecated January 21, 2025
Shutdown July 21, 2025 · 374 days ago
Status Retired
Last verified July 30, 2026

What to use instead

Anthropic Claude Sonnet 4.6 claude-sonnet-4-6 Provider-recommended Shutdown scheduled

Two full generations separate these models. Prompts written to compensate for Sonnet 3's weaknesses usually hurt rather than help on 4.6.

What parameters claude-sonnet-4-6 accepts on modelparams.dev

Change the id

In most cases the migration is one string. Check the parameter differences before you ship — newer models drop older sampling knobs more often than they add them. 

- "model": "claude-3-sonnet-20240229"
+ "model": "claude-sonnet-4-6"

Frequently asked questions

When did Anthropic Claude Sonnet 3 shut down?
Anthropic Claude Sonnet 3 shut down on July 21, 2025. API requests to it fail from that date onward.
What replaces Anthropic Claude Sonnet 3?
Anthropic recommends Claude Sonnet 4.6 (`claude-sonnet-4-6`) as the replacement for Anthropic Claude Sonnet 3. Two full generations separate these models. Prompts written to compensate for Sonnet 3's weaknesses usually hurt rather than help on 4.6.
Is Anthropic Claude Sonnet 3 still available?
No. Anthropic Claude Sonnet 3 is retired and no longer served — it was shut down on July 21, 2025. Calls to it return an error.
How do I migrate from Anthropic Claude Sonnet 3 to claude-sonnet-4-6?
Swap the model id in your API call: replace "claude-3-sonnet-20240229" with "claude-sonnet-4-6". Two full generations separate these models. Prompts written to compensate for Sonnet 3's weaknesses usually hurt rather than help on 4.6.

Sources

Found something wrong? The data is one YAML file — edit it on GitHub.

This page, for machines

JSON Markdown Badge JSON

Drop the badge in a README so it turns red the day this model is retired:

[![claude-3-sonnet-20240229](https://img.shields.io/endpoint?url=https://modeldeprecations.dev/badge/anthropic/claude-3-sonnet-20240229.json)](https://modeldeprecations.dev/anthropic/claude-3-sonnet-20240229)

Other Anthropic models

All Anthropic deprecations →

How to use this site

The full guide, in Markdown. Copy it and hand it to a coding agent verbatim.

# How to use modeldeprecations.dev

[modeldeprecations.dev](https://modeldeprecations.dev) answers one question per model: is it deprecated,
when does it shut down, and what replaces it. Every date on the site is cited to the
provider's own documentation, with the date we last checked it.

Three lifecycle states are used, matching the providers' own vocabulary:

- **active** — still supported, no deprecation announced.
- **deprecated** — the provider has announced it is going away. It still answers requests.
- **retired** — API access is gone. Requests fail.

A model can be active *and* carry a shutdown date: Anthropic publishes a
"not sooner than" date and Google publishes an earliest shutdown date for models
that are current and fully supported. Those are reported as scheduled shutdowns,
not deprecations, because that is what the provider actually committed to.

## Check one model

```bash
curl https://modeldeprecations.dev/api/v1/models/openai/gpt-4-32k.json
```

Or fetch the page as Markdown, which includes the answer, the dates and the sources:

```bash
curl https://modeldeprecations.dev/openai/gpt-4-32k.md
```

## Full catalog

```bash
curl https://modeldeprecations.dev/api/v1/models.json
```

Ids are `provider/model`. Dated snapshots (`gpt-4-32k-0613`) are listed as aliases of
their canonical entry rather than as separate records.

Each entry carries `computed_status`, the lifecycle state recomputed against the build
date — so a model whose shutdown has passed reads `retired` without anyone editing data.

## Badges

A shields.io endpoint per model, for READMEs that should go red when a model dies:

```
https://img.shields.io/endpoint?url=https://modeldeprecations.dev/badge/openai/gpt-4-32k.json
```

## Calendar and changelog

- Subscribe to every shutdown date: https://modeldeprecations.dev/calendar.ics
- Changelog RSS: https://modeldeprecations.dev/changelog.xml

## JSON Schema

```bash
curl https://modeldeprecations.dev/api/v1/schema.json
```

## Contribute

Data lives in YAML under `models/{provider}/{model}.yaml` in the
[GitHub repo](https://github.com/mnfst/modeldeprecations.dev). Every lifecycle date needs a source URL; CI rejects a
date without one. Open a PR.

## For agents

- Machine-readable overview: https://modeldeprecations.dev/llms.txt
- This guide plus every model inline: https://modeldeprecations.dev/llms-full.txt
- Any page also exists as Markdown: append `.md` to a model URL.
- In a browser, this site registers a **WebMCP** tool on `navigator.modelContext`:
  `check_model_deprecation`, `list_shutdowns`, `find_replacement`, and `get_usage_guide`.
- Parameters each model accepts are catalogued on the sibling site, https://modelparams.dev.