Common Mistakes I See in Node.js Backends (And How to Fix Them)

I've worked on enough Node.js backends at this point to start seeing the same problems come up over and over. Some of them are beginner mistakes. Some of them show up in codebases written by people who really should know better. Here are the ones I see most often. Not handling async errors properly This one is everywhere. Someone writes an async function, forgets to wrap it in a try/catch, and now unhandled promise rejections are silently swallowing errors in production. // this will swallow errors app . get ( " /users " , async ( req , res ) => { const users = await getUsers (); res . json ( users ); }); // this won't app . get ( " /users " , async ( req , res , next ) => { try { const users = await getUsers (); res . json ( users ); } catch ( err ) { next ( err ); } }); Better yet, use a wrapper utility or a library like express-async-errors so you don't have to repeat that pattern everywhere. Putting everything in one file I've opened Node.js projects where the entire app, routes, b