Prior existence
It proves that the file, with that exact content, already existed before the date and time of the seal. Your proof that you got there first.
File certification · eIDAS
Prove that a file already existed on a given date
The simplest way to generate technological evidence that a file —a creative work, a contract, a project, a plan— existed and has not been altered since a given moment. With four cryptographic fingerprints, time stamping and blockchain auditing.
Confidential? You can certify by sending only the hash, without uploading the file.
What it proves
Existence and integrity, with a certain date
A file certificate answers with precision two questions that may be worth a lawsuit.
Subsequent integrity
Any change to the file alters its fingerprint: the certificate lets you prove the document has not been modified since it was stamped.
To be precise: time stamping proves when a file existed and that it has not changed, not who its author is or its legal content. For authorship, combine it with the Safe Creative intellectual property registry or with an electronic signature.
Most valued by companies
Certify without revealing the content
The fingerprint (hash) is like the file's fingerprint: it identifies it uniquely, but does not let it be reconstructed. That is why you can certify by sending only the hash, without uploading the document. Ideal when the content is secret.
- The file never leaves your system: you certify only its fingerprint.
- Protects trade secrets, know-how, plans and sensitive data.
- When you need it, the hash of the original must match the certificate.
# You compute the hash on your machine
sha256(contrato.pdf)
→ a17c4e…e9f2
# You send only the hash to certify
POST /file/certify
{ "sha256": "a17c4e…e9f2" }
# You receive the stamped certificate
200 OK · eIDAS seal + blockchain
# The document is never uploaded
sha256(contrato.pdf)
→ a17c4e…e9f2
# You send only the hash to certify
POST /file/certify
{ "sha256": "a17c4e…e9f2" }
# You receive the stamped certificate
200 OK · eIDAS seal + blockchain
# The document is never uploaded
How it works
Three steps, evidence forever
Provide the file or its hash
Upload the file to Safe Stamper or, if it is confidential, send only its SHA-256 fingerprint.
Fingerprints and seal are generated
Four cryptographic fingerprints are computed and the electronic signature and time stamp are applied.
You receive the certificate
A certificate with the fingerprints, the date and the signature, backed by daily blockchain auditing.
Use cases
For everything that matters to prove it already existed
Works, projects and know-how
Leave a record that your creation, development or document existed on a date: manuscripts, designs, source code, business plans, formulas or R&D projects. Your basis to defend authorship and priority against copies or plagiarism.
Trade secret
Prove the existence and date of confidential information without revealing its content, sending only the hash.
Contracts and agreements
Fix the exact version of a contract or document on a date, avoiding disputes over later changes.
Plagiarism and infringement
Prove the priority of your work against anyone who copies it or claims its authorship.
Compliance and auditing
Stamp deliverables, records, logs or evidence to prove their integrity and timing before auditors or regulators.
Automation · API
Stamp files from your own systems
The perfect case for the API: certify at scale, automatically and without your documents leaving your environment.
- Integrate stamping into your ERP, document manager or pipeline (CI/CD, releases, backups).
- Send only the SHA-256 hash: the content never leaves your system.
- Arena testing environment (arena.safecreative.org): test with sandbox keys without consuming credits.
- Part of the Safe Creative and Safe Stamper API ecosystem.
API access is a professional channel with specific conditions according to the agreement signed; it is not part of the standard plans.
# Certify a file by its hash
curl -X POST https://api.safestamper.com/file \
-H "Authorization: Bearer ***" \
-d '{ "sha256": "a17c4e…e9f2" }'
# Response
{ "status": "certified",
"timestamp": "2026-06-17T11:04:22Z",
"eidas": true, "blockchain": true }
curl -X POST https://api.safestamper.com/file \
-H "Authorization: Bearer ***" \
-d '{ "sha256": "a17c4e…e9f2" }'
# Response
{ "status": "certified",
"timestamp": "2026-06-17T11:04:22Z",
"eidas": true, "blockchain": true }
The backing that gives confidence
Technology built to hold up
The evidence combines several fingerprints, signature and seal, with a daily audit that anchors each certificate in a public chain.
Complete the protection: for authorship use the Safe Creative registry; to sign documents, Safe Stamper Signature; for communications, Mail and Notify.
- Four cryptographic fingerprints that identify the file uniquely.
- Time stamping compliant with the European eIDAS regulation (EU 910/2014), which binds the data to an instant.
- Daily blockchain audit: the fingerprints are published on Ethereum for independent verification.
- Confidentiality: option to certify only the hash, without uploading the file.
- Evidentiary value: evidence admissible in courts and arbitration.
🇲🇽 For users in Mexico
NOM-151 conservation certificate included
If you operate from Mexico, every file you certify includes, in the same act, the Data Message Conservation Certificate in accordance with NOM-151, without contracting a separate provider. A double layer of evidence —the European seal and the Mexican certificate— over the same evidence.
IntegrityLets you verify that the data message has not been modified since the certificate was issued.
Technical certain dateLinks the evidence to a date and time verifiable through a qualified time stamp.
Verifiable conservationProves that the evidence existed at a given moment and keeps its digital fingerprint.
The NOM-151 certificate is issued through SeguriData, a Certification Services Provider accredited by Mexico's Ministry of Economy. Available for users in Mexico and for organizations in other countries that require it due to their activity in that market.
Plans and getting started
Stamp one file or thousands
Start with one-off certifications and move to subscription or API when stamping becomes part of your operations.
Prepaid credits
To certify one-off files, with no commitment.
- One credit per certified file
- Uploading the file or only its hash
- Certificate with evidentiary value
Monthly or annual
For recurring use and teams, with centralized history.
- Certifications for recurring volume
- Centralized management and lookup
- Foundation to automate via API
Mass stamping or API integration into your systems? The sales team prepares a tailored solution for your organization.
Talk to sales
Frequently asked questions
Common questions
Do I have to upload the file?
You must upload it so we can take its digital fingerprints. In that case, the document never leaves your system and you keep the evidence all the same. However, you can indicate that we do not keep it in custody and, therefore, it will not be stored in our system.
What exactly does it prove?
That a file with that exact content existed before the date of the seal (existence) and that it has not been modified since then (integrity). It does not by itself certify authorship: for that there is the Safe Creative registry or the electronic signature.
What does the certificate include?
Four cryptographic fingerprints that identify the file, the Safe Stamper electronic signature and the time stamp, backed by daily blockchain auditing.
How is it verified later?
By recomputing the fingerprint of the original file: if it matches the one in the certificate, it confirms that it is the same file and that it has not changed. The fingerprints are also recorded in the blockchain audit.
Can I automate it?
Yes. Through the API you can stamp files (or their hashes) from your ERP, document manager or pipeline, and test in the Arena environment without consuming credits. It is a professional channel with conditions according to agreement.
Does the evidence comply with NOM-151 in Mexico?
Yes. For users in Mexico, every file certification includes the Data Message Conservation Certificate in accordance with NOM-151, issued through SeguriData (a PSC accredited by the Ministry of Economy), in the same act and without additional contracting. It is also available for organizations in other countries with activity in that market.
What validity does it have as evidence?
It is technological evidence with evidentiary value, with eIDAS time stamping and a cryptographic fingerprint. Its assessment corresponds, as with all evidence, to the body that analyzes it.
Put a certain date on what you have created
Stamp your most important files today and have proof that they existed, intact, when it matters to prove it.
SafeStamper File is a service of Safe Creative, a global certification authority and trusted third party, operating since 2007. Time stamping proves the existence and integrity of the file on a date, not its authorship or its legal content. The certificates are technological evidence with evidentiary capacity; their assessment depends on the context, the jurisdiction and the criterion of the body or party that analyzes them, and they do not replace legal advice when necessary.
