Claude 3 Opus

Claude 3 Opus, API id claude-3-opus-20240229, is a retired Anthropic model. According to Anthropic's model deprecations page, Anthropic notified developers on June 30, 2025 that Claude Opus 3 would be retired, and the model was retired on January 5, 2026. Requests to a retired model fail, so any code that still calls this id must move to a current model. The recommended replacement on that page is claude-opus-4-8.

Status and Timeline

Anthropic's lifecycle terms are Active, Legacy, Deprecated, and Retired. Retired means the model is no longer available and requests fail. Anthropic also says it commits to long-term preservation of model weights, as described in its commitments on model deprecation and preservation.

What To Use Instead

Anthropic's models overview now recommends starting with Claude Opus 5.5 for most workloads and Claude Fable 5.1 for demanding reasoning and long-horizon agentic work. Claude Opus 5.5 is listed at $4 per million input tokens and $20 per million output tokens, with a 1M-token context window and 128K max output, as checked on 2026-10-29. See Claude Opus 5.5 and Claude Opus 4.6 in this catalog.

Migration Checklist

1. Search your code and configs for claude-3-opus-20240229 and the claude-3-opus family names.
2. Pick a replacement from the models overview, then read Anthropic's migration guide for it.
3. Re-run your own evaluations, since behavior, pricing, and supported parameters differ across generations.
4. Note that sampling parameters such as temperature, top_p, and top_k are removed in API version 2026-10-21 and return a 400 error, per the deprecations page.

FAQ

Is Claude 3 Opus still available?

No. Anthropic lists it as retired on January 5, 2026, and requests to it fail.

What replaced Claude 3 Opus?

Anthropic's deprecations page names claude-opus-4-8 as the recommended replacement. The current overview recommends Claude Opus 5.5 as the default starting point.

When was the retirement announced?

June 30, 2025, which gave developers roughly six months before the retirement date.

Can I still read about its specs?

Anthropic's current docs focus on active and legacy models. For retired models the deprecations page is the authoritative record.

Alternatives

• Claude Opus 5.5: Anthropic's current Opus tier.
• Claude Opus 4.6: an earlier Opus listed as active on the deprecations page.
• Claude Sonnet 5.5: the faster, lower-cost tier.

Conclusion

Claude 3 Opus is a retired model, kept here as a reference for teams cleaning up old integrations. Use the deprecations page as the source of truth and browse current options in the models category.