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Topics
Real-time
Pushing updates to clients the moment they happen.
Path
System design
Distributed systems
Articles
Level
Foundation
Core
Senior
Staff
Design questions only
Patterns
Two systems, two lifetimes
Claim with an expiry
Hot key
Fan out on write or on read
Cut the map into cells
Safe retries
Number every change
Serve from the edge
One owner per key
The answer that never came
Narrow
Reliability
1
Networking
2
Caching
1
Data modelling
1
Replication
1
Consistency
2
Transactions and locking
1
Concurrency
1
Queues and streams
3
API design
1
Location
1
India scale
1
LLMs
1
Agents
1
11 pages
Real-time connections at scale
System design · Core · 13 min
Networking
Design WhatsApp
System design · Core · 24 min
Queues and streams
Data modelling
Design a notification service
System design · Core · 32 min
Queues and streams
Reliability
Design Uber
System design · Senior · 38 min
Location
Transactions and locking
Design Google Docs
System design · Staff · 35 min
Consistency
Concurrency
Design live cricket score fan out
System design · Senior · 34 min
Caching
India scale
CRDTs
Distributed systems · Senior · 10 min
Consistency
Replication
WebSockets vs SSE vs polling
Articles · Core · 10 min
Networking
Push vs pull
Articles · Core · 8 min
Queues and streams
Webhooks vs polling
Articles · Core · 8 min
API design
Voice agents
Articles · Senior · 13 min
LLMs
Agents