Instagram

2 design problems known to be asked at Instagram.

Medium1

Mediumsystem design interview algorithms concurrency databases

Design a Distributed ID Generator

Auto-increment doesn't survive sharding, and random UUIDs wreck your database's index. How do you mint billions of unique, roughly time-sortable 64-bit IDs across a fleet with no coordinator? This is the Snowflake design — bit for bit.

Asked at Twitter, Instagram, Discord +2

Aug 9, 2026·16 min read

Hard1

Hardsystem design interview distributed systems caching scalability

Design a News Feed

The Twitter/Instagram timeline, worked end to end. The whole system pivots on one decision — do you build a follower's feed when someone posts (push), or when they open the app (pull)? Toggle between them, watch the write and read cost flip, and see why one celebrity breaks the naive answer.

Asked at Meta, Twitter, Instagram +3

Aug 9, 2026·13 min read