Building DocProof: Proving Documents Exist Without Sharing Them

There's a problem that's been bugging me for a while. How do you prove a document existed at a specific point in time—without handing it over to someone else?

Think about it: contracts, creative work, research notes, legal agreements. Sometimes you need proof that something existed before a certain date. Traditional solutions? Upload it to a notary service. Email it to yourself. Store it with a third party who pinky-promises to keep timestamps honest.

None of that felt right to me. Why should I trust a company to hold my documents? Why should proving when something existed require giving up what it contains?

So I built DocProof, with GoLang as backend API and worker, and Angular as the frontend.

The idea

DocProof lets you create a timestamped, verifiable proof that a document existed—without ever uploading the document itself.

Here's how it works:

1. You select a file on your device
2. Your browser computes a SHA-256 hash (a cryptographic fingerprint) of that file—locally, on your machine
3. That fingerprint gets anchored on the blockchain with a timestamp
4. Done. Your document never left your device. Only the fingerprint did.

Anyone can later verify the proof independently by hashing the same document and checking it against the blockchain record. No need to trust me, no need to trust DocProof to stay in business, no need to share sensitive content.

Why blockchain?

Blockchain carries some baggage. NFT speculation, crypto hype, environmental concerns.

Blockchain is genuinely good at one specific job—creating immutable, timestamped records that don't depend on any single party. That's exactly what document verification needs.

DocProof uses Base, a Layer 2 network on Ethereum. It's proof-of-stake (no massive energy consumption), cost-effective, and permanent. The proof exists independently of whether DocProof as a service continues to exist.

There's no token, no NFT, no financial element, no crypto speculation. Just a timestamp you can trust.

Is this like an NFT?

I get this question, and it's fair. There's technical overlap: both use blockchain to create timestamped, immutable records. Both involve cryptographic proof of something existing on-chain.

But the purpose is completely different.

NFTs are about ownership and transferability. You mint something, you can sell it, trade it, speculate on it. The whole ecosystem is built around digital assets changing hands—often with significant financial speculation attached.

DocProof is about proving existence at a point in time. That's it. No trading. No marketplace. No speculation. You're not buying or selling anything. You're creating a verifiable timestamp.

There's also a key privacy difference: NFTs typically store or link to the actual content (an image, a video, metadata). DocProof only stores the hash—a cryptographic fingerprint. The document itself never leaves your device, and the hash reveals nothing about the content. You can't reverse-engineer a document from its hash.

Think of it like the difference between selling a painting and getting a document notarized. Same pen, completely different purpose.

Who is this for?

I've been thinking a lot about use cases:

Freelancers and contractors — Prove when you delivered work or signed an agreement. Useful if disputes arise later about timelines.

Creators and inventors — Establish proof of creation for designs, music, writing, code, patents. Show that your work existed before someone else claims it.

Researchers and academics — Timestamp research findings, papers, or data before publication. Protect priority claims.

Legal and compliance — Contracts, wills, insurance policies. Proof that a version existed at a specific moment.

Anyone who values privacy — You might just want a personal record without trusting a third party with your files.

What's next

DocProof is live now, and I'm actively working on it. The core functionality works: create proofs, verify them, all without uploading your documents anywhere.

I'm building this because I think it should exist. Privacy-first and practical.

If you want to try it out, head over to docproof.org.

I would love feedback—what works, what doesn't, what use cases I haven't thought of.

And if you're curious about the technical details or want to follow along as I build, I'll be posting updates here and on Mastodon.

Let's see where this goes.

/Daniel