API Versioning

Why do so many APIs treat backward compatibility as someone else's problem?

When you ship a v2, you're handing every integrated developer a refactoring project they didn't ask for. It's your architectural cleanup at their expense. Stripe decided that's not acceptable — so every account gets pinned to the date it was created. A transformation layer walks the current data model back to match exactly what that version expected. Code written in 2011 still runs. You never have to upgrade. Think of it like a power grid: you don't change the voltage every two years and then bill your customers for the electrician.

The cost nobody talks about

Breaking changes aren't free. They're a tax — on developer time, on trust, on the relationship between you and the people building on top of you. The question worth asking: who should absorb that cost, the platform or the builder? I think the platform should. Always. The moment you make someone else upgrade so you can refactor, you've made their problem your leverage.

Why this is hard to copy

Pulling this off requires an internal compatibility layer, isolated version modules, and a transformation system that knows the full history of your data model. It's expensive to build and nearly impossible to fake late. That's why it's a moat — not the feature, but the commitment behind it.

The API that never breaks is the one everyone eventually builds on.