Software

Design a reliable cache

A cache stores a computed result so the next request can skip the slow work. The design problem is freshness: when the saved result is no longer the right one.

For engineers preparing system design discussions or adding a cache to an API and wanting the failure modes in writing.

Start here

Read the HTTP caching guide, then pick one response in a system you know and write its freshness rule and its invalidation rule.

Recommended resources

Start here · Intermediate

HTTP caching

Freshness, validation, and revalidation, explained on the protocol most web caches speak.

developer.mozilla.org Map · Intermediate

System Design Primer: cache

A compact map of where caches sit, eviction, and the failures interview questions usually probe.

github.com Go deeper · Intermediate

Two Hard Things

A short note on why naming and cache invalidation stay hard even after the happy path works.

martinfowler.com