Is this proof enough to force a client to pay?

No. The timestamped proof establishes the file's existence date, which significantly strengthens your position in a dispute. But recovery depends on your contract and legal avenues. It's a solid piece of evidence, not direct legal compulsion.

Is my deliverable file sent to your servers?

No, never. All processing happens locally in your browser. Only the cryptographic fingerprint (SHA-256) — a unique identifier that cannot reconstruct your file — is transmitted for timestamping.

Can I timestamp a deliverable after sending it?

Yes, but the timestamp will be after the sending. Ideally, certify BEFORE sending to prove the file existed at a date prior to delivery.

Is this proof admissible in a commercial court?

The RFC 3161 certificate constitutes technical proof of priority. Combined with your contractual exchanges, it's a solid element for establishing a deliverable's existence date in a commercial dispute.

Should I tell my client I use ProofStamper?

Not required, but recommended. Mentioning the timestamped proof in your delivery email has a powerful deterrent effect on bad-faith clients.

Client refuses to pay claiming late delivery — How to protect yourself

You delivered on time — but can you prove it?

You worked hard, met the agreed deadlines, and sent your deliverable on time. But when it's time to invoice, the client claims the delivery was late to justify a penalty, a reduction, or a refusal to pay. Maybe the email got lost in spam. Maybe the client is acting in bad faith. Either way, without independent timestamped proof of the file's existence and sending date, you're in a weak position. A simple email can be challenged, a screenshot can be faked, and mail servers don't always keep the necessary records.

Responding to payment refusal: your concrete options

Gather all existing proof of delivery: emails with timestamps, read receipts, messages on work platforms.
Find the signed contract or quote specifying deadlines and delivery conditions.
Send a formal demand by registered email citing available evidence.
Contact a freelance association or a lawyer specialized in debt recovery.
For amounts under €5,000, file with the small claims court without a lawyer.

ProofStamper cannot resolve an ongoing dispute — it protects for the future. For an active dispute, consult a legal professional or freelance association.

A delivery email can be challenged — an RFC 3161 proof cannot

In a commercial dispute, a bad-faith client will systematically challenge evidence whose date can be questioned. An email can be backdated or claimed as never received, a screenshot can be manipulated, a Slack or Teams message can disappear. Only a timestamp from an independent trusted third-party authority, using the open RFC 3161 standard, produces technically unassailable date proof verifiable by any expert.

Next time, certify every deliverable before sending

I'm finalizing a deliverable before sending it to the client.

I generate a timestamped proof of the file in 30 seconds before any sending.

I can prove this deliverable existed at this exact date, before any sending to the client.

The file never leaves my device. Only the SHA-256 fingerprint is transmitted.

Every delivery deserves proof of date

Mockups and designs
Development and code
Written content
Videos and edits
Reports and audits
Final production files

How to deliver a file with attached proof

Finalize and certify: Finalize your deliverable and generate the timestamped proof on ProofStamper.
Send with certificate: Send the client the deliverable + PDF certificate + .tsr file as attachments.
Mention in your email: State 'This deliverable is accompanied by a verifiable RFC 3161 certified timestamped proof'.

This simple mention in the email deters the majority of bad-faith clients.

Which delivery proof to choose?

Four approaches compared.

Criterion	Standard email	Freelance platform	Registered letter	ProofStamper
Cost	Free	Included	€5–10	Free
Delay	Instant	Instant	48–72h	30 seconds
Falsifiable	Yes	Difficult	Difficult	No (RFC 3161)
Third-party verifiable	No	Yes (platform)	Yes (postal)	Yes ✓
All formats	Yes	Limited	Paper	Yes ✓
Usable off-platform	Yes	No	Yes	Yes ✓

3 steps before each delivery

Drop your finalized deliverable: PDF, ZIP, images, videos, code — all formats accepted.
Automatic local certification: SHA-256 hash computed in browser + RFC 3161 timestamp via FreeTSA.
Download your Proof Pack: PDF certificate + .tsr token. Attach them to your delivery email.

Frequently asked questions

Is this proof enough to force a client to pay?: No. The timestamped proof establishes the file's existence date, which significantly strengthens your position in a dispute. But recovery depends on your contract and legal avenues. It's a solid piece of evidence, not direct legal compulsion.
Is my deliverable file sent to your servers?: No, never. All processing happens locally in your browser. Only the cryptographic fingerprint (SHA-256) — a unique identifier that cannot reconstruct your file — is transmitted for timestamping.
Can I timestamp a deliverable after sending it?: Yes, but the timestamp will be after the sending. Ideally, certify BEFORE sending to prove the file existed at a date prior to delivery.
Is this proof admissible in a commercial court?: The RFC 3161 certificate constitutes technical proof of priority. Combined with your contractual exchanges, it's a solid element for establishing a deliverable's existence date in a commercial dispute.
Should I tell my client I use ProofStamper?: Not required, but recommended. Mentioning the timestamped proof in your delivery email has a powerful deterrent effect on bad-faith clients.