Caching
A shop ledger page, 1899. Every line adds up.
LLD Series: LRU / LFU Cache (Low-Level Design)
Phrasings: LeetCode 146/460 but as a class design, Design an in-memory cache like Guava/Caffeine, cache BIN/merchant/config lookups. Asked heavily at Visa, Mastercard, NPCI, Amex, PayU...
15 min read
How to Add Redis Caching to an API Without Serving Stale Data Forever
Choose cache keys, TTLs, invalidation rules, and stampede protection for API responses while accounting for stale data and cache failures.
4 min read
Why Your Next.js App Router Data Is Stale and How to Control Caching
Understand why App Router pages show outdated data, how revalidate and force-dynamic behave, and how caching defaults differ between Next.js 14 and 15.
5 min read