Social & Feed

Design Instagram (Focus on Photo Storage and CDN)

A photo-sharing platform optimized for write-once/read-many media delivery via multi-resolution transcoding and aggressive edge caching.

Core Architectural Components

Accepts uploads and hands them to the processing pipeline.

Generates multiple resolutions/formats from each original.

Durable blob store holding originals and every derived variant.

Serves images from a point of presence near the viewer.

Post, user, caption, and tag data separate from the binary image data.

Assembles the personalized feed from the follow graph and recent posts.

Backbone of both the feed and discovery surfaces.

Eventually-consistent high-throughput counters that don't hot-spot the post record.