Design: URL Shortener

Mon, 06 Apr 2026 16:27:00 +0530

Started learning system design and architecture seriously. I’ll be posting daily notes on whatever i learn about the subject going forward. Here’s the first one–enjoy!

1. The Core: Base62 Encoding

To keep URLs short, we use Base62 encoding ([a-z, A-Z, 0-9]).

A 7-character string gives us 3.5 Trillion combinations.
Why not Base64? Base64 includes + and /, which are not URL-safe and can break paths.

2. The Coordination Problem: Key Generation Service (KGS)

In a distributed system, we must prevent “collisions” where two servers generate the same ID.

Vijay Pagare's Diary on Vijay Pagare

Design: URL Shortener

1. The Core: Base62 Encoding

2. The Coordination Problem: Key Generation Service (KGS)