The API as a Product

An API has users. Its users are developers.

They arrive with a job, form an opinion in minutes, make mistakes, and decide whether the product is worth trusting. They may never speak to the team that built it.

So an API is not successful because every operation works when its author calls it correctly. It succeeds when a stranger can discover the right operation, send a valid request, understand the result, recover from failure, and survive change without asking the authors for help.

Four qualities make that possible: consistency, useful errors, fast onboarding, and responsible deprecation