An alternative to the e-Soleau envelope
By BlockchainSignLast updated
The e-Soleau envelope is France's official way to establish anteriority: you deposit files with INPI, the national industrial property institute, and they are archived and dated by the state. It carries real institutional weight. It also has two properties worth understanding before you choose it — you hand over the file, and the record has an expiry date.
What e-Soleau is
INPI's electronic successor to the paper Soleau envelope. You upload files through INPI's portal, they are fingerprinted and archived, and you receive a dated deposit that establishes you held that content on that date.
Pricing is €15 for a deposit of up to 50 MB, with higher bands for larger files (€25 up to 100 MB, €35 up to 150 MB). You choose a conservation period of 5, 10, 15 or 20 years, and the deposit can be renewed up to three times.
It is genuinely useful in a French context. It is run by the state, IP practitioners in France know exactly what it is, and it needs no explaining to a French court. That last point is worth a great deal and we cannot match it.
The two properties to weigh
You upload the file. This is the fundamental difference and it is not a criticism — INPI archives the content because archiving is the service. But it means the file leaves your control. For a great many documents that is entirely fine. For a pre-patent design, an unannounced brand, a client deliverable under NDA or a confidential financial document, "who else now has a copy" is exactly the question the deposit was supposed to help with.
Our model never receives the file. The hash is computed in your browser with the Web Crypto API and only that 64-character string is transmitted; there is no upload endpoint for the file at all. You can confirm it in your browser's network tab.
The record expires. e-Soleau conservation runs for a chosen period and is renewable up to three times — so a maximum of 80 years if you keep paying and keep remembering. A blockchain transaction has no expiry, no renewal and nothing to forget. It is either in the ledger or it is not, and it will be.
| e-Soleau (INPI) | BlockchainSign | |
|---|---|---|
| Who holds the file | INPI archives it | Nobody — only the hash is sent |
| Cost | €15 up to 50 MB, more above | $9.99 for one, $3.00 each at 100 |
| Duration | 5–20 years, renewable ×3 | Permanent, no renewal |
| Recognised by | French institutions and courts | Anyone who can read a block explorer |
| Verification | Through INPI | Directly on Etherscan, no vendor |
| Jurisdiction | France | None in particular — a public ledger |
| Proves | The content was deposited on a date | The file existed on a date, unchanged |
Which to use
Honestly: if you are in France, the matter is likely to be decided in France, and the content is not especially sensitive, e-Soleau is a good choice and its institutional recognition is worth more than anything we can offer. We would rather say that than pretend otherwise.
A blockchain timestamp is the better fit when the confidentiality is the point, when the counterparty or the forum is outside France, or when you want a record with no expiry and no dependence on any institution's continued operation.
They also combine well. Depositing with INPI and timestamping gives you a state-archived copy and an independent public record of the same file, and the second costs a few dollars.
What neither one proves
Both establish that specific content existed by a date. Neither proves you created it, and neither creates a right — see proof of existence vs proof of authorship. INPI is explicit about this too: the envelope is proof of anteriority, not a title.
For how blockchain timestamps are actually being treated by European courts, including the 2025 Marseille decision, see is a blockchain timestamp valid in court.