Overview
CommitProof is a timestamping service that lets you prove a piece of text or a file existed at a specific point in time without ever revealing what it is. It is built for inventors, designers, writers, and founders who want a cheap, public record of "what I knew, when" — for example, before sharing an early draft, design, or business idea. The service stores only a one-way fingerprint of your content on the blockchain, so the original never leaves your device1.
CommitProof is a single-operator project run by Tommy Kammerer (Neuried, Germany) and listed in the official Cardano apps directory under the Notary category23. It works on the Cardano mainnet and is shipped in English, German, Japanese, and Spanish.
Key Features
- Public, tamper-proof record of when something existed. Each proof is a Cardano transaction that includes a one-way fingerprint (a SHA-256 hash) of your content. The block timestamp acts as the official "when," so anyone can later confirm the proof was created at that exact time4.
- Your content never leaves your browser. The hashing happens locally using your browser's built-in cryptography. Only the resulting fingerprint and a random salt are sent to the signing-and-verification layer on Cardano1.
- Pay with ADA or a card. Each proof costs 3 ADA plus the standard Cardano network fee (around 0.18 ADA). Payment works from a Cardano wallet — including Eternl, Lace, and Typhon — or with a credit card, Apple Pay, or Google Pay. No subscription, no account1.
- Downloadable proof file you control. Every commit produces a PDF and a JSON file containing the transaction hash, your original text, and the salt. You keep these locally to verify the proof later or to share with a lawyer, a partner, or a court4.
- Public proof index anyone can audit. A single CommitProof address on Cardano receives every proof transaction, and the site's Proof Explorer lists them. Activity is visible to anyone, and the project is listed in Cardano's official app directory2.
What to Expect
A first-time visitor lands on a clean, two-button homepage: "Create Proof" or "Verify." Creating a proof is a short, in-browser flow — type the text or pick a file, confirm a 3 ADA payment, and download the resulting PDF and JSON file. There is no email signup and no account.
Verification works the same way in reverse: upload the proof file (or paste the transaction hash, original text, and salt), and the site recomputes the fingerprint and compares it to what is on the blockchain. The whole experience is one short page each way, and the FAQ explains every step in plain language — including how to confirm in your browser's developer tools that your content really never gets uploaded1.
CommitProof does not issue a token, run smart contracts, or stake any ADA — it is a simple paid utility on top of Cardano transaction metadata, with the technical stack and operator clearly disclosed in the site's legal notice3. The FAQ also collects the legal context for blockchain timestamps, citing the EU eIDAS Regulation, a 2025 French court ruling5, and rules issued by China's Supreme Court in 20186. It is explicit that a timestamp is supporting evidence, not a replacement for a patent or copyright registration.
