Anthropic Claude Opus 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 program ask another for something. Think of a vending machine: you press buttons, and it gives you a snack without you seeing the inner workings. Apps use APIs the same way, requesting weather data or maps from other services.

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, Supabase Auth, or AWS Cognito. With two people, your scarcest resource is focused engineering time, and authentication is a deceptively deep problem: password hashing, session management, token rotation, MFA, account recovery, rate limiting, and a steady stream of security patches. Getting any of it wrong can end a young company, and none of it differentiates your product. A hosted provider gives you a secure, compliant baseline in an afternoon, letting you spend your energy on what customers pay for. The strongest argument against this is lock-in. Your user table becomes someone else's database, pricing often jumps once you pass free-tier limits, and migrating later can be painful because password hashes and session logic may not export cleanly. If the provider raises prices or shuts down, you inherit an urgent, risky migration exactly when you have real users to lose.