Building a Privacy-First URL Shortener on Blockchain

Description and use

A privacy‑first URL shortener that encrypts links client‑side, stores them on the Cronos blockchain, and decrypts in the browser, eliminating server‑side tracking and data breaches.

Problem

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

Outcome

Cryptly delivers a privacy‑first URL shortener that stores encrypted URLs on a blockchain, preventing server‑side tracking, data breaches, and censorship.

Workflow

• 1. User enters a URL in the Cryptly web interface.
• 2. The browser generates a random IV and AES‑GCM key using Web Crypto API.
• 3. The URL is encrypted client‑side and the ciphertext is sent to a Cloudflare Worker.
• 4. The Worker writes the ciphertext to the Cronos blockchain via a smart‑contract transaction.
• 5. The Worker returns a short code (hash) to the user.
• 6. When the short code is visited, the Worker fetches the ciphertext from the blockchain.
• 7. The browser decrypts the ciphertext locally and redirects to the original URL.
• 8. No server logs or analytics are collected.
• 9. The system remains censorship‑resistant and tamper‑proof due to blockchain immutability.

Evidence

Encrypted URL stored on Cronos blockchain

Source

Server never sees destination URLs

Source