Building REST APIs Other Teams Actually Want to Use

Summer 2026 · ~4 min read

Every API I'd built before this summer had one consumer I controlled: a frontend I also wrote, or a script only I ran. This summer, working on GoDaddy's Observability Platform team, that changed — the consumers of the endpoints I shipped were other engineers, on other teams, who would never read my code and would only ever see the contract.

That's a small sentence with a large set of consequences. Here's what actually changed about how I wrote APIs once that was true.

The contract is the whole product

When you own both sides of an API, a bad response shape is annoying but fixable in five minutes. When you don't, a bad response shape is a Slack message to a team you don't work with, a delay on their end, and a slower fix on yours because now you're coordinating a change instead of just making one. Consistent schemas, predictable pagination, and validation errors that say exactly what's wrong stopped being nice-to-haves and became the actual deliverable — the code behind the endpoint was almost secondary.

Documentation is not an afterthought

I started writing architecture and usage docs while I built, not after — partly because I knew I wouldn't remember the reasoning behind a decision two weeks later, and partly because the doc was often the only thing another engineer would read before deciding whether to trust the endpoint at all. A well-documented API with a slightly worse implementation beats a well-implemented API nobody can figure out how to call.

Tests are part of the definition of "done"

On a personal project, I'd sometimes treat tests as a follow-up task. On a platform other teams build on, an untested endpoint is a liability the moment it ships, because the blast radius of a regression isn't your own time — it's every team that already integrated against you. Unit and integration tests became part of what "shipping an endpoint" meant, not something that happened after.

The takeaway

None of this is a new idea — it's the standard advice for building internal platforms. What surprised me was how much it changes your instincts in the moment, mid-implementation, when the fast path and the responsible path stop being the same path. Choosing the second one consistently is, I think, most of what "production-grade" actually means.