Off-market verification — how PocketLister proves it.
The PocketLister promise has one binding condition: the home really is off-market. To enforce that — to refund a buyer’s €99 with confidence, or to invoke the 2% breach clause against a seller — PocketLister needs to prove a public listing existed. Below is the exact six-step evidence protocol used for every introduction and the audit trail retained.
When the check runs
For every Quiet Profile and every introduction, the verification is run automatically at three moments:
(i) When the Seller opens a Quiet Profile — baseline check against the home’s description, Catastro reference, and uploaded photos.
(ii) At the moment an introduction is opened to a Buyer — the live check that founds the Match Agreement.
(iii) On a rolling cadence (no less than weekly) for the full one-month window after introduction.
The six-step evidence ladder
Each rung is captured, retained in tamper-evident form, and delivered to both parties if a breach is identified.
Portal HTTP capture
The raw HTML response from every portal queried — Idealista, Fotocasa, Kyero, Rightmove, James Edition, Engel & Völkers, Lucas Fox, Drumelia, Marbella Estates, and any other agency website returned by the property-search crawl. Each capture includes request URL, response status, response headers, and full body, with a UTC timestamp.
Source · PocketLister evidence storeFull-page rendered screenshot
The matching portal page is rendered in a headless Chrome browser at 1440×900 and captured as a PNG. The screenshot includes any agency branding, asking price, photos, Catastro reference, and the URL bar — rendered as a court would see it. The PNG is sealed with a SHA-256 hash recorded in the Evidence Packet manifest.
Source · Playwright + ChromiumPerceptual photo-hash match
PocketLister computes a 64-bit perceptual hash (dHash) for every photo the Seller uploads to their Quiet Profile, and for every photo on any candidate portal listing. A Hamming distance of ≤ 6 between two hashes means the two images are functionally identical — the same photo, even if cropped, recompressed, or watermarked. The match table is reproducible from the raw photos; the Seller can recompute it themselves.
Source · dHash algorithm · reproducibleCatastro / address fuzzy match
The Catastro reference, urbanization name, calle/street, and postcode from the Seller’s Quiet Profile are tokenised and compared against the portal listing’s address fields using normalised edit distance. A confidence score (0–100) is recorded. Combined with the photo-hash match in step 03, a confidence above 75 with a photo-hash match is treated as the same property.
Source · PocketLister address matcherIndependent third-party archive
At the moment of capture, the matching portal URL is submitted to the Internet Archive’s Wayback Machine (web.archive.org/save/). The returned snapshot URL and its timestamp are stored alongside our own capture. The Wayback snapshot is held by a neutral third party, time-stamped by the Internet Archive’s own infrastructure, and is independently retrievable by the Seller — or anyone — without trusting PocketLister.
Source · Internet Archive Wayback MachineCryptographic timestamp on the Bitcoin blockchain
The SHA-256 hash of the entire Evidence Packet (steps 01–05) is submitted to a public OpenTimestamps server and anchored to the Bitcoin blockchain. The returned proof file (.ots) is stored alongside the packet. This proves that the evidence existed at or before the block’s timestamp — without trusting PocketLister, the courts, or any single party. The proof is verifiable by anyone using the open-source OpenTimestamps client.
Source · OpenTimestamps · Bitcoin blockchainWhat the Seller receives if a breach is found
If the verification matches a public listing to the Seller’s property, PocketLister delivers a Breach Notice within seven days. The notice contains:
1. The Evidence Packet (steps 01–06 above), zipped.
2. The matched portal URL(s) and the date of the match.
3. A perceptual-hash comparison report — the Seller’s photo and the portal photo, side-by-side, with the computed Hamming distance.
4. The Wayback Machine snapshot URL.
5. The OpenTimestamps .ots proof file.
6. PocketLister’s computed liquidated-damages figure under clause 08 of the Match Agreement.
The Seller’s right to respond
The Seller has fourteen days from receipt of the Breach Notice to provide a written explanation. Legitimate explanations include:
· A previous listing taken down before the introduction (PocketLister’s sweep should have caught this; a mistake on our side is correctable).
· An unauthorised duplicate by a third-party agent without the Seller’s knowledge or consent.
· A portal data error — a photo or address mistakenly attributed to the wrong property.
· A photo that appears in the Seller’s public portfolio (architect, designer, magazine feature) without indicating the property is for sale.
PocketLister reviews any such explanation in good faith. Where the Seller’s account is corroborated, the Breach Notice is withdrawn, the Buyer’s €99 stays charged, and no breach fee is invoked. Both parties are notified in writing of the outcome.
Why this combination holds in court. A screenshot alone is disputable. An HTML download alone is editable. But the combination of (i) a perceptual photo-hash match the Seller can reproduce, (ii) an independent Wayback Machine snapshot held by a neutral third party, and (iii) a blockchain-anchored timestamp that proves the evidence existed at or before a specific block — collectively constitutes evidence that survives any single-party tampering claim. Under Spanish civil procedure (LEC art. 299.2 and Real Decreto-ley 14/2019), this stack is admissible electronic evidence.
What this is not
This protocol does not determine whether a Buyer can or cannot proceed with a purchase, nor does it cancel a sale that the parties wish to complete. It determines two things only: (a) whether the Buyer’s €99 unlock fee is refunded under clause 07 of the Match Agreement, and (b) whether the 2% liquidated-damages fee under clause 08 applies if a sale completes. Everything else is between Buyer and Seller.
Questions
If you have a question about how a specific verification was carried out, or you’ve received a Breach Notice and want to provide an explanation, email [email protected]. PocketLister’s outside Spanish counsel is on the same address.