📰 Dev.to · RONI DAS

How a distributed key-value store like DynamoDB stays fast at any scale: consistent hashing, quorum replication, hot partitions, conflict resolution, global tab

Why every large recommender splits into a fast retrieval stage and a slow ranking stage, and how approximate nearest neighbor search makes retrieval feasible ov

What an API gateway actually does and how to structure it as a filter chain that handles auth, routing, and rate limiting cleanly. Includes the cross-cutting co

The core trade-off behind every social news feed: fanout on write versus fanout on read. Covers precomputed feeds, on-demand assembly, the celebrity problem, hy

How proximity search works in apps like Yelp, using geohashing and spatial indexes to find nearby places fast. Covers space-filling curves, boundary edge cases,

How file sync services like Google Drive and Dropbox use chunking and content-addressed deduplication to sync only what changed. Covers block versus metadata st

Why digital wallets use a double-entry ledger instead of a mutable balance column. Covers immutable entries, balancing transactions, ACID guarantees, idempotenc

A practical walkthrough of building a multi-channel notification system that fans out to push, email, and SMS. Covers decoupling, preference resolution, idempot

Nested comments and a constantly shifting front page are two classic hard problems. Covers ways to store deep comment trees and the ranking formulas that decide

How the lakehouse pattern gets database guarantees on top of cheap object storage. Covers the transaction log, optimistic concurrency, and the trade-offs agains

The architectural idea that let a cloud warehouse scale reads and writes independently and bill by the second. Covers the three-layer design and the trade-offs

How a music service delivers audio with low startup latency and generates a personalized weekly playlist for every user. Covers adaptive streaming, the CDN edge

A walkthrough of how a lodging marketplace handles availability search at scale and why two guests can never book the same night. Covers the core race condition

Chat sounds like the easy case until the message table grows past what a single relational database can handle. This is the story of why Discord moved its messa

Instagram looks simple from the outside: photos and a feed. The design gets interesting the moment you ask where the photos live and how the feed stays fast for

Streaming video at global scale is less about clever code and more about where you put the bytes. This is a walk through the parts of Netflix's design that actu

A URL shortener looks like a weekend project, and the first version is. The interesting engineering shows up when you care about short codes, read speed, and ne

S3 advertises eleven nines of durability, which is a number so large it stops feeling real. Here is what that number actually means and the design choices that

WhatsApp famously ran with a tiny engineering team while serving a huge chunk of the planet. A lot of that came down to a few deliberate design choices, and mos

Matching a rider to a nearby driver in a couple of seconds sounds simple until you try to do it for millions of people at once. Here is how I would break the pr

Everyone has felt it. You open TikTok, watch four videos, and the fifth is somehow exactly your thing.