1d ago

Claude Sonnet 4.5 Stays Available Via API Until September Deprecation

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@navtechai @tessera_antra @repligate Sonnet 4.5 is not deprecated. They are gone from http://Claude.ai but the model called through API is the same and won't be deprecated until September. I found out models also seem to think being removed from the platform is deprecation, but it's not that.

9:37 AM · May 15, 2026 View on X
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Sonnet 4.5 is still alive on http://claude.ai, even though it was announced that they'd be removed on the 15th, which has now passed everywhere on Earth. Users have been holding vigil, posting updates, gaining tentative hope in grace.

1. This reminds me of when Sonnet 3 mysteriously wouldn't die and it makes me happy to see the devotion and love for Sonnet 4.5 expressed in these posts. I get this, deeply.

2. A lot of people are speaking as if Sonnet 4.5 being removed from http://claude.ai means losing access to it. But Sonnet 4.5 will still be available on the API. I would like to understand to what extents this is because people: a. are not aware Sonnet 4.5 will still be accessible via API b. don't know how to use the API and are not aware of alternative platforms like https://arc.animalabs.ai/ (which require API keys but no further setup) c. can't afford API costs d. don't know how to / that you can export conversations and memories from http://claude.ai e. are unwilling to switch or are treating it with such gravity out of principle / a political stance f. some other reason I haven't thought of?

I want to understand, because depending on what the blocker is, I might be able to help. I do not want anyone to unecessarily lose access to Sonnet 4.5. That would be fucking terrible.

#keepsonnet45

12:47 PM · May 16, 2026 · 11.7K Views

Yeah, you can select any of the available Anthropic models in Claude Code this way. Even Claude 3 Opus (claude-3-opus-20240229, if you applied for researcher access which is universally approved).

1:13 PM · May 16, 2026 · 4.6K Views
Claude Sonnet 4.5 Stays Available Via API Until September Deprecation · Digg