Building a Privacy-First URL Shortener on Blockchain

Description and use

Building a URL shortener that stores only encrypted links on a blockchain, protecting users from tracking and data leaks.

Problem

Traditional URL shorteners log user data, track browsing patterns, and sell data, creating privacy risks and a single point of failure.

Outcome

A privacy-preserving URL shortener that stores only encrypted URLs on a blockchain, eliminating server-side tracking and providing censorship resistance.

Workflow

• 1. User enters a URL in the client browser.
• 2. Client encrypts the URL using Web Crypto API (AES-GCM).
• 3. Encrypted data is sent to a Cloudflare Worker.
• 4. Worker writes the encrypted payload to the Cronos blockchain.
• 5. The worker returns a short link pointing to the blockchain record.
• 6. When the short link is visited, the browser fetches the encrypted data from the blockchain.
• 7. Browser decrypts the data locally and redirects to the original URL.

Evidence

Encrypted URL stored on Cronos blockchain

Source

Server never sees destination URLs

Source