Cracking the Code: Building an Advanced URL Shortener from Scratch (No Third-Party APIs!)

1. URL Shortener in System Design Interviews
Many interviewers commonly ask about designing a URL shortener in system design rounds. This is because it involves handling scalability, database design, hashing algorithms, and high-traffic APIs. Candidates are expected to discuss how they would generate short URLs, manage collisions, handle redirections efficiently, and scale the system for millions of users.

2. Typical Approach by Developers
When developers build a URL shortener, they often rely on backend APIs to generate short URLs. Most implementations use third-party services like Bit.ly, TinyURL, or Firebase Dynamic Links, while others build a basic backend that maps long URLs to short ones using a database.

3. My Approach: A Fully Custom URL Shortener
Instead of relying solely on third-party APIs, I built a URL shortener from scratch, implementing my own logic for:

Custom Keyword-based Short URLs – Users can define their own custom short links instead of random hashes.

QR Code Generation – Every shortened URL automatically gets a scannable QR code for easy sharing.

Optimized Database & Hashing Algorithm – Ensuring that short links remain unique and efficient.

By designing everything from the ground up, I gained deeper insights into how URL shorteners work at a system level and optimized the experience for specific use cases.