Anthropic Claude Sonnet 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 agreed rules that lets one piece of software ask another for something. Think of a wall outlet: you don't need to know how electricity is generated, you just plug in following the standard shape. Similarly, apps send requests in a set format and receive predictable answers.

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.

Use a hosted provider such as Auth0, Clerk, or Supabase Auth. Authentication is a solved problem with an unforgiving failure mode: a subtle mistake in password hashing, session handling, token expiry, or account recovery can expose every user you have. A two-person team has no spare capacity to build, audit, and maintain password resets, social logins, multi-factor authentication, and rate limiting, and none of that differentiates your product. Hosted providers give you all of it in days, with security teams watching for new attack patterns. Your limited engineering time belongs on what customers actually pay for. The strongest argument against this is lock-in and cost at scale. Your user identities, and the login flows built around them, become dependent on a vendor whose pricing, policies, or existence can change. Per-user fees can balloon as you grow, and migrating password hashes and sessions later is painful. Choosing a provider with data export and standard protocols reduces, but does not eliminate, that risk.