When the seller flips the price after you've agreed.
The classic Vinted / Depop / Marketplace pattern: a back-and-forth chat lands on €40, you commit, and a day later the seller messages 'I actually meant €60, I never said €40.' If the platform supports it, the chat history is your evidence — but platforms purge, accounts get banned, and screenshots without provenance are easy to dismiss as edits. A receipt seals the chat-screenshot at the moment of agreement: a SHA-256 + ECDSA signature anchored externally minutes later. The dispute team at PayPal / Vinted / your bank can verify the timestamp predates the seller's flip. The receipt won't make the seller honest — it just makes the lie cost more than it's worth.
When this scenario hits you
- Vinted / Depop / Mercari chat where the price was agreed in DMs but the listing was never updated to reflect it.
- Facebook Marketplace pickup where the buyer ghosts after agreement, then opens a 'item not as described' claim against your bank statement.
- Custom-order chat where the maker quoted a price, you paid the deposit, and they then claim 'the deposit was for design only, the build is extra.'
- Apartment-rental chat where the landlord agreed to take an item off the deposit list, then deducts for it anyway at move-out.
- Friend-to-friend sale ('I'll let you have it for €100') where the friendship sours and the seller now wants the 'real' €150.
What you actually do
- 01
Screenshot the message where the agreement was made, in full context.
Include the timestamps the platform shows, both sides' messages, and ideally the message immediately before and after so the agreement reads in context. If the price was negotiated over several messages, screenshot the whole exchange — receipts hash bytes, so a long screenshot is one signed proof for the entire conversation.
- 02
Seal the screenshot in /seal the same day.
The hash + signature happen in your browser and on our worker; the image bytes never leave your device. Within thirty minutes the OpenTimestamps anchor lands and the timestamp is publicly provable.
- 03
Save the stamped image and the receipt URL alongside any proof of payment.
PayPal receipt, bank statement line, or Vinted-internal order ID — keep them in one folder. If a dispute kicks off, you'll want all three together: agreement (sealed), payment (statement), and any follow-up (sealed too).
- 04
If the seller flips, paste the receipt URL into the dispute or chargeback form.
PayPal, Wise, Revolut, and bank dispute forms all accept URL evidence. The dispute reviewer can verify the timestamp at the URL, see the signed proof, and verify the seal predates the seller's claim. They don't need to trust you — the cryptography speaks.
- 05
For small-claims, the receipt is a clean exhibit.
Print the receipt page; it shows the timestamp, the SHA hash, the verifier output, and the public-key link. Pair it with the original screenshot file on a USB stick — the clerk can drop it on /verify and confirm in fifteen seconds.
Why the receipt holds
- The seal happens within minutes of the conversation; the OpenTimestamps anchor makes the timestamp un-forgeable shortly after.
- Both PayPal and Vinted's dispute teams already accept screenshot evidence — adding a signed, timestamped layer makes the evidence weigh more, not less.
- Verification is one-click for the dispute reviewer: drop the file on /verify, get back identical, recompressed, or mismatch in under a second.
- If the platform purges the chat (it happens — Vinted auto-deletes inactive conversations after months), the sealed screenshot is your independent copy.
Where the receipt stops
- It doesn't prove the seller's account was actually controlled by the seller. Account compromises happen — though they're rare in dispute fact patterns.
- It doesn't change platform-side TOS. If Vinted requires in-platform-only agreements for buyer protection, an out-of-band DM agreement may still not qualify for their refund — even sealed.
- It doesn't bypass the dispute window. PayPal's 180-day chargeback window applies regardless of how cleanly you sealed evidence. Move quickly.
Specific questions about this scenario
Does PayPal / Vinted actually accept this as evidence?
Yes — both already accept screenshot evidence. A receipts.you-stamped screenshot is still a screenshot; the cryptographic timestamp is bonus credibility, not a separate evidence category. Paste the receipt URL in the 'additional evidence' field if the dispute form has one, or attach the stamped image directly.
What if the seller blocks me after I seal — do I lose access to the chat?
Your sealed copy is independent. Blocks affect future conversation, not files you already saved. Seal early and often is the right pattern for in-progress negotiations you don't trust.
Can I seal a recording of the chat instead of a screenshot?
Receipts seal still-image files. For a screen-recording video, seal a representative still frame plus the video itself if your hosting supports hashing video files. We don't yet hash MP4 directly; the v1 product is screenshot-focused.
Will it work for international marketplaces (Mercari Japan, Leboncoin France)?
Yes — receipts are platform-agnostic. We hash pixel bytes regardless of source. As long as the dispute body accepts foreign-language screenshots, the cryptographic layer applies the same.
If the seller also seals their version, who's right?
Two opposing receipts can coexist; both are valid timestamps. The dispute body weighs the content. Receipts don't pre-judge truth — they only fix when each file existed. Concurrent receipts from buyer and seller usually clarify the timeline more than either party expected.
Related scenarios
Seal the agreement before the dispute starts.
Drop the chat screenshot, walk away with a dated, signed proof. PayPal-acceptable, Vinted-acceptable, court-acceptable.