Building a Privacy-First URL Shortener on Blockchain

Description and use

Cryptly is a privacy‑first URL shortener that encrypts links client‑side, stores them on a blockchain, and decrypts locally, eliminating data collection and central databases.

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 encrypts URLs client‑side, stores them on a blockchain, and decrypts them locally, eliminating server‑side tracking and central database risks.

Workflow

• 1. User enters a URL in the Cryptly web interface.
• 2. The browser generates a random IV and derives an AES‑GCM key via 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 as an immutable record.
• 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 using the same key and IV, then redirects to the original URL.
• 8. No server logs the destination URL or user data.
• 9. The system is censorship‑resistant and has no central database to hack.

Evidence

Bit.ly logs your IP, timestamp, user agent

Source

Encrypted URL stored on Cronos blockchain

Source