Anthropic Claude Haiku 5.5

Explain what an API is to someone who has never written code. Do not use a restaurant or waiter analogy. Plain prose only — no headings, bullet points, or markdown formatting. Maximum 50 words.

An API is a set of rules that lets one piece of software ask another for information or services in a standard way. Think of it as a published list of requests a program understands, along with the format of the answers it will send back. Your weather app, for example, uses one to fetch forecasts from a weather service.

A two-person startup is deciding whether to build their own user authentication or use a hosted provider. Give them a clear recommendation, then the single strongest argument against your own recommendation. Plain prose only — no headings, bullet points, or markdown formatting. Maximum 150 words.

My recommendation is to use a hosted authentication provider such as Auth0, Clerk, or Supabase Auth. Authentication is a security-critical problem where subtle mistakes, like flawed password reset flows, session handling bugs, or weak credential storage, can expose every user at once. Two people cannot realistically match the attention that specialized providers give to these areas, and building it yourselves diverts time from the product that actually differentiates your startup. Hosted providers also handle compliance features, multi-factor authentication, and social login out of the box, and you can migrate later if needs change. The strongest argument against this recommendation is cost and lock-in. Per-user pricing can climb steeply as the startup grows, sometimes becoming a significant line item before revenue justifies it. Moving off a provider later means migrating password hashes, sessions, and user identifiers, which vendors often make difficult, so early dependence can quietly constrain future decisions.