Backend Principles

See what happens when a browser makes an HTTP request with an interactive visualization. Follow DNS resolution, the TCP and TLS handshakes, the request hitting a server route, middleware, the database, and the response coming back.

See how database indexes speed up queries with an interactive visualization. Compare a full table scan against a B-tree lookup, watch the tree descend to a leaf, and see why writes get slower as indexes pile up.

See how caching works with an interactive visualization. Watch cache-aside hits and misses, write-through updates, TTL expiry, LRU eviction, and the stale data problem that makes invalidation hard.

See how JWT authentication works with an interactive visualization. Watch login produce a signed token, the header, payload, and signature get encoded, a protected route verify the signature, and an expired or tampered token get rejected.

See how rate limiting protects an API with an interactive visualization. Watch a token bucket refill and drain, a fixed window reset at the boundary, a sliding window smooth out bursts, and requests get accepted or rejected with 429.