How to Build a URL Shortener/Bitly Architecture

Introduction

Design and architecture questions similar to this one are somewhat rarer than algorithm questions on interviews but can give interviewers a tremendous insight into how the interviewee thinks and how they would approach problems in practice.

These questions are not meant to be studied in and of themselves. Instead, you should pay attention to different considerations, principles, ideas, and patterns. Because of this, we'll go through a lot of bad ideas just to illustrate why they're a viable pattern in general, but not good for our purposes.

Bitly is not open source and this article is in no way affiliated with them nor do we have insight into their actual architecture. But what we aim to do is figure out how to theoretically make a similar system.