Launching today
Doc Notary
Notarize any file with a tamper-proof on-chain hash
1 follower
Notarize any file with a tamper-proof on-chain hash
1 follower
Seal a file's SHA-256 fingerprint on a public blockchain, without putting the file on-chain. Anyone can verify a copy in their browser, free and with no account.
Launch Team
Framer AI AgentsDesign and publish professional sites with AI
Promoted
I've been building something since August, and it's now live: Doc Notary.
The problem: you often need to show that a file existed at a certain time, unchanged. A manuscript before submission, a design before a client dispute, a dataset before publication. Emails and cloud timestamps are easy to question.
Doc Notary records a file's SHA-256 fingerprint on a public blockchain with a timestamp. The file itself never goes on-chain; only its fingerprint does. Later, anyone can drop a copy into their browser and check it. If even one byte changed, it won't match. No upload and no account needed to verify.
What I built:
• React frontend, Node.js/Express API, Supabase (Postgres + Auth), Cloudflare R2
• A Solidity smart contract, with transactions paid by the service, so users don't need a crypto wallet
• PDF proof certificates, usage limits, bot protection, and paid plans through Kelviq
It's in beta on the Ethereum Sepolia test network, and the Free plan covers 3 notarizations a month.
If you work with journals, research, or client deliverables, I'd love your feedback: https://www.doc-notary.com
#buildinpublic #blockchain #webdevelopment #research