Building a Privacy-First URL Shortener on Blockchain

Description and use

A privacy‑first URL shortener built with client‑side encryption and blockchain storage to eliminate data logging and central points of failure.

Problem

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

Outcome

Cryptly provides a privacy‑first URL shortener that eliminates server‑side logging, removes a single point of failure, and offers censorship‑resistance via blockchain storage.

Workflow

• Generate a random IV and AES‑GCM key in the browser
• Encrypt the destination URL with Web Crypto API
• Send the ciphertext and IV to a Cloudflare Worker
• Worker writes the ciphertext to the Cronos blockchain via a smart contract
• User accesses the short URL, Worker retrieves ciphertext from blockchain
• Browser fetches ciphertext, decrypts locally, and redirects to the original URL

Evidence

Encrypted URL stored on Cronos blockchain

Source

Server never sees destination

Source