Privacy policy for the PropertyFacts browser extension.
View the Project on GitHub mariosbikos/propertyfacts-privacy
Last updated: 31 July 2026
PropertyFacts is a browser extension that adds public property data to listings on spitogatos.gr. It is not affiliated with, authorised by, or endorsed by Spitogatos.
PropertyFacts has no server, no account, and no analytics. The developer does not receive user data. Extension data stays in your browser profile and is deleted when you remove the extension.
All extension data lives in chrome.storage.local on your device. The extension does not transmit stored settings or cached results to the developer.
| What | Why | Retention |
|---|---|---|
| Your settings (on/off, language, light/dark) | To remember your choices | Until you change or uninstall |
| Cached public data about map areas (amenities, transport, administrative areas, air quality, seismic history, land registry, forest map) | Avoid repeat requests for the same area | 30-180 days by source; oldest entries are dropped when cache storage exceeds 6 MB |
| Optional zone value entered by you | Remember the value for that neighbourhood when calculating the ENFIA estimate | Until you change it or uninstall |
The current release does not create price history records.
You can clear cached public-data results at any time from the extension toolbar popup (“Clear cached data”). Settings and optional zone values remain until you change them or remove the extension; removing the extension deletes all extension data.
To describe a listing’s surroundings, the extension asks public data services about a location — a latitude and longitude. It never sends the listing URL, the listing ID, a price, an identifier, or anything about you.
| Service | Operator | What is sent |
|---|---|---|
QLever OSM (qlever.dev) |
University of Freiburg | The listing’s coordinate |
Overpass API (overpass-api.de, overpass.private.coffee) |
OpenStreetMap community | The listing’s coordinate |
Overpass API fallback (maps.mail.ru) — see below |
VK (Russia) | The listing’s coordinate |
Open-Meteo Air Quality (air-quality-api.open-meteo.com) |
Open-Meteo | A coordinate rounded to about 1 km |
USGS Earthquake Catalog (earthquake.usgs.gov) |
U.S. Geological Survey | A coordinate rounded to about 1 km |
Hellenic Cadastre (services-eu1.arcgis.com, gis.ktimanet.gr) |
Ελληνικό Κτηματολόγιο | The listing’s coordinate; the map image request is made only when you open the aerial photo |
Amenities, transport and administrative areas are looked up on QLever first; the Overpass servers cover terrain (coast, forest, roads) and stand in for QLever when it is slow. Both receive the same coordinate and nothing else.
It is the position the listing itself publishes, and for most listings that is already an approximate one: the site offsets the pin by roughly 300–500 m, and the panel labels those listings “approximate”. Some listings publish an exact pin, and for those the coordinate is the building.
Two of the services above receive less than that. Air quality is read from a roughly 11 km climate grid and seismicity is a count within a 100 km radius, so neither answer changes if the point moves a kilometre — the extension rounds the coordinate to about 1 km before sending it to them, because it costs nothing.
The others cannot be coarsened without making the answer wrong: a walking time is not a walking time if the starting point moved 700 m, and the cadastre parcel is a specific piece of ground. Those services receive the coordinate as published. An earlier version of this page said every service got a rounded coordinate; that was not true of the amenity and cadastre lookups, and saying so plainly is better than a comforting sentence the code did not honour.
These are third-party services with their own privacy practices, and each will see your IP address as any website you visit does. The extension sends them no identifier of any kind, so they cannot link one request to another or to you beyond what your IP already reveals.
maps.mail.ru fallbackThe OpenStreetMap community’s own Overpass servers are heavily overloaded and
periodically refuse or queue requests. maps.mail.ru is the only other free
full-planet Overpass instance there is, and it is run by VK, a Russian company.
It is a last resort, not a mirror in rotation. A request goes there only after the community servers have been tried and failed within the same request, which is the difference between a panel that works and one that shows nothing. What it receives is the same as what the other Overpass servers receive: the listing’s coordinate as described above, and nothing else — no listing, no identifier, no account. If you would rather that never happen, turn the extension off on the listings you do not want looked up; there is no partial mode.
On a results page the extension may look up the surroundings of a listing you have not opened yet, so the panel is already filled in if you click it. It is the same request with the same coordinate and nothing else, it is capped at one area per page, and it yields to real requests — but it does mean a coordinate can be sent for a listing you only scrolled past. Turning the extension off stops it.
Listed buildings, traditional settlements and Greek regional statistics are bundled inside the extension, so looking them up sends no request at all.
User-Agent (and Referer)
on requests to the four OpenStreetMap Overpass and QLever hosts, whose usage
policies ask clients to identify themselves. It is used for nothing else and
applies only to those hosts.The panel footer contains a single optional donation link, which opens Buy Me a Coffee in a new tab. It is an ordinary external link: nothing is behind a paywall, no feature is withheld, and the extension has no payment processing of any kind. Nothing is sent to that service unless you click the link.
PropertyFacts is a tool for property research and is not directed at children.
Material changes to this policy are published at https://mariosbikos.github.io/propertyfacts-privacy/, where the full revision history is public.
Questions or corrections: mariosbikos@gmail.com