← System Design
Object / Blob Storage
StorageDurable, infinitely-scalable storage for unstructured binary data (images, video, backups) accessed by key, not by path/query.
Object storage (S3, GCS, Azure Blob) stores immutable blobs of data addressed by a flat key, with rich metadata, at massive scale and very high durability (often 11 nines), typically via erasure coding or multi-region replication under the hood. Unlike a file system, there's no real directory hierarchy (keys just contain '/' characters that get displayed as if they were folders) and unlike a database, there's no querying by content — you fetch by key.
How it connects
Object / Blob Storage as the source, with the components it typically interacts with.
- → CDN (Content Delivery Network): Object storage is the canonical origin behind a CDN — static assets are uploaded once and served at the edge on cache miss.
- → Database Types (SQL, NoSQL & Beyond): Large blobs (images, videos, attachments) are stored in object storage while the database only stores a pointer/URL to keep row sizes small.
- → Message Queues & Event Streaming: Uploads to object storage often trigger an event (e.g. S3 event notifications) published to a queue for async processing (thumbnailing, virus scan, indexing).