Anthropic has just bought a startup whose tools were used by virtually all of its biggest competitors - OpenAI, Google, Replicate, Runway and Cloudflare. The price has not been officially disclosed, but according to The Information, the acquisition of Stainless was worth more than 300 million dollars (about 275 million euros).

Stainless is a hidden but crucial part of the modern AI industry's infrastructure. Founded in 2022 in New York by Alex Rattray, a former Stripe engineer, the company automates the creation and maintenance of SDKs (software development kits) that allow external developers to plug into the APIs of large AI companies. In plain terms - when OpenAI ships a new version of its API, Stainless automatically updates the tools developers use to talk to it.

The platform turns API specifications into ready-made SDKs across nearly every major programming language: Python, TypeScript, Kotlin, Go and Java. What used to take a team of ten engineers, Stainless does in a few hours.

Here's where it gets interesting. Anthropic will shut down all hosted Stainless products. Which means OpenAI, Google and everyone else will have to either move to their own solution, or ask their competitor to keep the access open. Existing clients keep the SDKs already generated for them - but not new ones. A textbook closed-access play: buy the pillar, then pull it out from under everyone.

Rattray, the founder, commented on the acquisition in neutral terms: "SDKs deserve as much care as the APIs they wrap. Anthropic was one of the first teams to bet on that with us." Translation: we were close, we sold for a good price, we're carrying on under Anthropic's roof.

For Balkan and European startups that depend on Stainless, this is a signal that shouldn't be ignored: AI infrastructure is consolidating at speed, and the space for independent tools is shrinking. When the game is played at 300 million dollar acquisitions, there's not much room left for independent players.