MoreThanCodebase
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1 min read

Build a Modern Messaging System

A practical system design case study inspired by WhatsApp-scale messaging platforms.

Author: MoreThanCodebase

What you will learn

  • Real-time delivery and offline handling
  • Group messaging fan-out trade-offs
  • Presence, receipts, media, multi-device sync
  • Encryption and scaling patterns

Articles in this series

  1. Introduction
  2. Functional Requirements
  3. Non-Functional Requirements
  4. High-Level Architecture
  5. Sending a Message
  6. One Write vs 1024 Writes
  7. Typing Indicator
  8. Blue Ticks
  9. Delete for Everyone
  10. Edit Message
  11. Online Status
  12. Media Sharing
  13. Multi-Device Sync
  14. Voice Calls
  15. End-to-End Encryption
  16. Scaling to Billions
  1. 1. Introduction1 min read
  2. 2. Functional Requirements1 min read
  3. 3. Non-Functional Requirements1 min read
  4. 4. High-Level Architecture2 min read
  5. 5. Sending a Message2 min read
  6. 6. One Write vs 1024 Writes5 min read
  7. 7. Typing Indicator2 min read
  8. 8. Blue Ticks3 min read
  9. 9. Delete for Everyone3 min read
  10. 10. Edit Message2 min read
  11. 11. Online Status2 min read
  12. 12. Media Sharing3 min read
  13. 13. Multi-Device Sync2 min read
  14. 14. Voice Calls4 min read
  15. 15. End-to-End Encryption2 min read
  16. 16. Scaling to Billions1 min read