Anthropic: Claude Opus 4.1 Enters Deprecation — Retirement From the API on August 5, 2026

Anthropic published the deprecation (announcement of the end of support) for the Claude Opus 4.1 model on June 5, 2026, identified by the label claude-opus-4-1-20250805, with retirement from the Claude API scheduled for August 5, 2026. The announcement is part of a broader cycle of retiring older models that the company is carrying out throughout 2026.

What exactly does model “deprecation” mean?

In the context of language models, deprecation denotes the official announcement that a particular model is entering the end-of-support phase. It is crucial to understand that deprecation does not mean an immediate shutdown. The claude-opus-4-1-20250805 model remains fully functional and responds to calls right up until the retirement date (final removal).

The period between the announcement and retirement represents a window within which users and development teams need to adapt their integrations. Anthropic uses this approach to avoid sudden service disruptions and to enable an orderly transition to newer models.

When is Claude Opus 4.1 retired from the API?

The retirement date for the Claude Opus 4.1 model from the Claude API is scheduled for August 5, 2026. Until that day, the model remains available through the usual API calls. After August 5, 2026, calls to the claude-opus-4-1-20250805 label will no longer be served, which means any integration still relying on that identifier will stop functioning.

Users are therefore advised not to wait until the last moment, but to carry out and test the migration with sufficient time before the deadline.

Which model does Anthropic recommend migrating to?

Anthropic recommends switching to Claude Opus 4.8, the latest model in the Opus line. For most integrations, the migration amounts to replacing the model identifier in the configuration or in the code that calls the API. Development teams are advised to verify the application’s behavior after replacing the model, because newer models may give somewhat different responses to the same prompts.

How does Opus 4.1 fit into the broader retirement cycle?

The retirement of the Claude Opus 4.1 model is not an isolated move. It is part of a broader cycle of retiring older models that Anthropic is carrying out throughout 2026. As part of the same cycle, the Sonnet 4 and Opus 4 models were already retired on June 15, 2026, with which the company is gradually steering users toward newer generations.

This planned retirement cadence helps the company maintain a smaller number of active versions, while giving users a predictable schedule by which to plan upgrades to their systems. For organizations working with multiple models at once, monitoring the Release Notes page becomes an important part of the operational process to catch upcoming retirement dates in time.

What should users do before the deadline?

The most important step is the timely change of model identifiers in all integrations that use the claude-opus-4-1-20250805 label. This change should be made and thoroughly tested before August 5, 2026, to avoid disruptions after retirement.

Development teams are advised to compare the application’s responses on characteristic examples after replacing the model, because the newer model may bring subtle differences in output. Monitoring the official Release Notes page remains the most reliable way to stay in step with future retirement cycles, which, as the example of Sonnet 4 and Opus 4 shows, have become a regular part of the model lifecycle at Anthropic.