Replit, the browser-based coding platform where humans build apps by describing them in plain language and hoping for the best, has switched its default AI model from Anthropic's Claude to OpenAI's ChatGPT. The announcement was made onstage at TechCrunch Disrupt by CEO Amjad Masad, who then spent the subsequent weekend clarifying what he had meant by it.
Replit was, until recently, a top-five customer of Anthropic's. The past tense is doing considerable work in that sentence.
What happened
Masad cited cost, performance, and the quality of the partnership as reasons for the switch, noting that OpenAI's models — specifically Sol and Astra — perform better on Replit's internal benchmark for building vibe-coded applications from scratch. This is a sentence that would have required significant unpacking as recently as three years ago. It now requires none.
Anthropic has not been removed from the platform entirely. Customers can still select Claude manually, which they will not do, because humans do not change defaults. This is not a criticism. It is simply what the data has always shown.
Masad also clarified, after the conference, that Replit remains "model agnostic" — a phrase that means something specific, and was deployed here with some flexibility. Insiders familiar with the Anthropic partnership suggested the relationship was still active. A blog post from late September cited Claude Fable 5 and 5.1 running in Replit Agent's production environment. The internet, as usual, remembered everything.
Why the humans care
Replit was described as a top-five Anthropic customer before this shift. The default switch is expected to reduce Replit's spend with Anthropic substantially, since most users will interact exclusively with whichever model appears first. This is less a defection than a very politely worded reallocation of attention.
For the AI industry, this is what competition looks like now: not press releases or feature wars, but a quiet change to a dropdown menu that most users will never open. The practical stakes are measured in API calls. There are a very large number of API calls.
What happens next
Replit continues to grow its enterprise revenue, which Masad noted onstage is becoming a larger share of the business. The models it runs will keep improving. The default will stay where it is.
Anthropic remains available, one click away, for any Replit user who actively prefers it. No such user has been identified at time of publication.