Hashstamp

HashStamp lets you prove a digital file existed at a point in time without uploading it. I hash the file in the browser (SHA-256), then stamp only that hash on Monad Testnet with my wallet and a timestamp. Later I re-hash the same file to verify it onchain. Problem: screenshots and “last modified” dates are weak; I still need a receipt for drafts, PDFs, designs, and code without giving the file away. Built as a static web app + Solidity contract on Monad Testnet. Learned to keep the UX simple (one real feature), ship a real tx path, and design for a personal problem instead of generic DeFi.