Open source blockchain evidence that a file exists at a certain date

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Open source, Built on Blockchains

How it works

Certify on Blockchain

Use tProof to publish a privacy-preserving hash of a file on blockchain. This proves that the file exists at certain date, certifying the document date with an open source and transparent approach. Anything can be a file: emails, PDFs, websites, photos, videos, procedures and much more.

Easy to find

Each certification is stored on chain in the form of a dedicated NFT. In this way, you won't rely just on us to access your certifications, avoiding any lock-in. You are the true owner, always able to independently access them.

Publish your files, or keep them private

Solution is privacy-focused and te content of the file is not published on chain. You can either decide to store the certified files privately, or make them public. We do also offer custom private file storage services.

Try it yourself

Simple and intuitive, directly from your web browser.


We have adopted industry standard algorithms, generating multiple proofs at the same time, all independently reproducible

Proof of Timestamp
Proof of Existence
Proof of Ownership


Certifications are recorded as NFTs, owned by you at blockchain level. They will last forever thanks to blockchain everlasting storage

Pay once, own forever
Certifications in your wallet
Repeat for any amount of files

Open Source

Smart contracts are open source and verified. This is why we've adopted open ecosystems like Ethereum and Polygon

Open source code
Smart contract based
Transparent interaction

Built for everyone

Everlasting certifications

tProof is studied to manage billions of certifications, as it's based on major technologies such as EVM-compatible blockchains (like Ethereum and Polygon) and Arweave for permanent file storage.

Blockchains (like Ethereum) is where the certification happens: by storing file hash, our smart contracts certify the date of your file. Within one transaction we're able to certify file ownership, content and date.

Traditional solutions generate proofs with a proprietary Certificate, that can be invalidated for multiple reasons. When this happens, all previous certifications expires. Blockchain certifications solves this problem, as including the hash into a block equals to store it forever.

Upfront single cost

Pay once, own forever

A big advantage of blockchain technology is how efficient it is to manage data for long-term storage, with a single upfront payment (transaction cost).

While traditional centralized storage services obliges you to keep paying to maintain valid your documents (and certifications), blockchain technology is different. Once the certification has been generated, you'll see it in your wallet and you'll own it for decades. Ideally, forever.

Our certifications are NFT-based, meaning that you can access them from any service that allows you to see the NFTs within your wallet. This makes you feel comfortable as you're not relying on a centralized service.


Integrate with other solutions

Either you are a business, system integrator, software house, company or a Web3 project, you can integrate our solution.

We offer both native blockchain integration, or simplified APIs, along with the support of our technical team. Make sure to read the Docs to understand key technical details, and feel free to reach out for any need.



Hash certification

Anonymous, decentralized service
Own your certifications
NFTs to simplify management
Choose descriptive metadata
Optional public availability of file, forever
ChainLink file hash certification
from (≈85$)
$ 3/cert(≈85$)
Cloud Platform

Business & Enterprise

Cloud platform
Fully automated
Pay with credit card
Private file storage
API-based integrations
from (≈85$)
$ 0.89/cert(≈85$)
Contact us


Anonymous, decentralized service
NFT-based proof
Own your proof
Choose descriptive metadata
Public availability of file, forever
ChainLink file hash certification
$ 40/cert (≈85$)

Meet the Team

Solidity Dev &
IT Architecture &

Frequently asked questions

Why a Timestamp Proof?

What is a hash?

Is hashing safe?

How does your pricing work?

Customers & Use Cases