TypeScript catches your mistakes before your users do

Imagine writing an essay where the spell-checker only runs after you've printed and mailed it. That's what building without TypeScript feels like. You write something, ship it, and then a user finds the typo. TypeScript is the spell-checker that runs while you're still typing. It catches a whole class of mistakes — wrong data types, missing fields, mismatched expectations between parts of your app — before anything goes live.

Every product is made of pieces that talk to each other. A button sends data to a form, the form sends it to a server, the server sends back a response. TypeScript makes sure all those pieces agree on what they're sending and receiving. When they don't agree, it tells you immediately — not three screens away, not two days later in a bug report. This is especially important when AI tools are helping you write code, because they write fast and can introduce subtle mismatches that are hard to spot by eye.

If you're starting a new project with a modern framework like Next.js, TypeScript is already the default — you don't have to set anything up. For an existing project, you can adopt it gradually, one file at a time. The key is to turn on strict mode from the beginning. It's much harder to add strictness later than to start with it. Think of it like organizing your desk: easier to keep it clean than to clean it after six months of chaos.

Any project that will live longer than a weekend experiment. The upfront cost is small — a few extra annotations here and there — but the payoff compounds over time. Every time you change something, TypeScript shows you everywhere that change ripples through your project. Without it, those ripples become bugs your users discover for you.