Design47 min
Merging concurrent edits so every copy converges to the same state.Pushing updates to clients the moment they happen.Persistent two-way connection between browser and server.Core featuresFull-duplex over one TCP connectionServer push, no pollingLow per-message overheadStateful: sticky, harder to load-balanceWhen to useChat, live collaboration, multiplayerLive feeds, presence, notificationsServer must push without being askedKeeping data correct when many requests touch it at once.Cheap, durable storage for files and blobs, like S3.Core featuresExtreme durability (11 nines)Virtually unlimited scaleLow cost per GB, storage tiersPresigned URLs for direct uploadsWhole-object writes, no in-place editsWhen to useUser uploads, media and backupsLarge files rather than queryable recordsData lakes and long-term archives
PremiumFigma
A browser-based design tool where hundreds of people can be in one file, every drag shows up on everyone's screen within a fraction of a second, and a file with millions of layers still opens.
What they’re really testing: A Figma file isn't text. It's a tree of millions of objects, each with dozens of properties, edited by up to 200 people at once and streamed at 30 updates a second while someone drags. Text-editor answers, OT or a character CRDT, solve the wrong problem, and the file may not even fit in the browser tab. How do you make every copy converge, lose nothing, and open fast?
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What’s inside
- Primary concepts and the hard part
- Requirements
- API / Model
- High-level architecture
- Trade-offs and deep dives
- Possible follow-up questions