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
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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