URL Shortener System Design
System design for a URL shortener service like Bitly. Covers API Gateway routing, write and read service separation, global counter for short URL generation, database schema, and Redis caching strategy.
url shortenersystem designmicroservicescachingredis
Requirements
Functional
- Users can create short urls from original urls
- Optional custom alias
- Optional expiration time
- Users can access the original url by visiting the short url
Non-Functional
- Ensure uniqueness of short urls
- Low latency redirection
- Availability >> consistency
- Scalable to 1B urls and 100M DAU
Author
Published
February 16, 2026
Last updated February 16, 2026