What rate limiting is, with a bucket analogy anyone can follow — then how I built a distributed token-bucket limiter in NestJS + Redis with a live dashboard that shows requests getting throttled in real time.
Rolling your own auth is usually a mistake — but when you must, the details decide whether it is secure. Here is the access/refresh token + MFA design I built in NestJS, with the pitfalls that bite.
Real-time chat and a live calendar planner are easy on one server and surprising on three. Here is how I designed Socket.IO features in a NestJS ecosystem — rooms, presence, and scaling across instances.