Terms of service

The services of cenostat.pl are provided by its author, Aliaksei Kashynski. Contact: prywatnosc@cenostat.pl.

We publish data on sales of units from the Property Price Register of the City of Warsaw and statistics calculated from it:

• on the cenostat.pl portal — a price overview and a description of the method;
• in the app at cenostat.pl/warszawa — on the map, in the analyses and in the list of transactions with filters;
• through the API at cenostat.pl/api/v1 — in JSON format, read-only.

The services are free of charge and require no account. You enter into the contract for the provision of services when, after these terms have been made available to you, you use the app or send a request to the API. A link to these terms is in the footer of every page and in the Link header of every API response. The contract ends when you stop using the service.

We may stop providing the services or change the API, announcing it on the home page at least 14 days in advance, unless security of the service or the law requires a faster change. We may stop providing the services immediately to anyone who breaks these terms.

The portal works without JavaScript. The app requires a current version of Chrome, Edge, Firefox or Safari with JavaScript enabled. Any HTTPS client is enough for the API.

Connections to the service are encrypted (HTTPS), your browser loads the basemap from OpenStreetMap servers (Privacy), and the data may be wrong, so check it at the source before an important decision. The app stores in the browser (localStorage) only the selected language and the state of the map panel; the service does not use cookies.

Transaction data comes from the Property Price Register kept by the Mayor of the City of Warsaw. We convert its coordinates to WGS84, assign transactions to neighbourhoods and flag sales that do not show the market price of a unit; the details are on the How we calculate prices page. Otherwise the data is unchanged from the register; we do not fill in missing values.

The data may be incomplete or wrong: deeds reach the register with a delay, the register sometimes contains mistakes, and we remove a transaction when the person it concerns objects. Prices and statistics refer to past sales and are not a valuation of a property.

The API is public and needs no key. From one IPv4 address or one IPv6 /64 network you may send at most:

• 240 requests per minute;
• 16 requests at a time;
• 30 requests per minute for map layers (/transakcje/budynki, /transakcje/obszary-msi), not counting responses the server already holds in memory.

When a limit is exceeded, the server responds with status 429.

You may use the data from the service and the API for any lawful purpose, including commercial purposes, under the rules below; this does not apply to the texts and design of the service's pages.

When you publish the data or work based on it, give the source, e.g. “Data source: Property Price Register, City of Warsaw, as of [date], via cenostat.pl”, and if you have processed the data, say so. Do not suggest that cenostat.pl prepared or endorses your work. The price register is made available free of charge and without a licence, subject to the obligation to give the source (Art. 40a(2)(1)(k) and Art. 40c(3) and (5) of the Polish Act of 17 May 1989 – Geodetic and Cartographic Law).

Transaction data may be personal data (Privacy). Anyone who processes it for their own purposes — stores, analyses, publishes or combines it with other data — is its controller under the GDPR and is responsible for compliance, unless they use it solely for personal or household purposes (Art. 2(2)(c) GDPR). You may not use the data to identify buyers or sellers or to contact them, e.g. for marketing.

We remove transactions subject to an objection from the service and the API. If you store downloaded data, refresh it at least once a month and delete transactions the API no longer returns. The rules in this section continue to apply after you stop using the service.

Other materials have their own sources and terms:

• basemap in the app: © OpenStreetMap contributors, ODbL licence (openstreetmap.org/copyright);
• neighbourhood boundaries: City Information System (MSI) areas, City of Warsaw, as of 22 October 2026, converted to WGS84, topologically repaired and simplified (tolerance about 5 m), under the city's terms of reuse;
• boundaries on the map of Poland: National Register of Boundaries (PRG), GUGiK, retrieved on 26 October 2026, free of charge and without a licence, with the source given (Art. 40a(2)(1)(a) and Art. 40c(3) and (5) of the same Act).

You may not send unlawful content to the service or disrupt its operation, including circumventing the API limits, e.g. by spreading the requests of one program across many IP addresses. It is not circumvention when the browsers of your website's users each send requests from their own address.

We may block an IP address (for IPv6, a /64 network) from which these rules are broken for as long as needed to protect the service, at most 90 days. If a block affects you wrongly, e.g. on a shared network, write to us and we will handle it as a complaint.

Write to prywatnosc@cenostat.pl. Describe the problem and give the page address or the API request. We will reply by e-mail within 14 days of receiving the complaint.

Matters concerning personal data, including objections to the publication of a transaction, are handled under the rules and time limits set out on the Privacy page.

We publish a new version on this page with the date from which it applies. Use of the service before that date is governed by the previous version, which stays available at an address with the date from which it applied, e.g. cenostat.pl/en/terms/2026-10-28/.

The contract is governed by Polish law. The service is run by a private individual, on a non-commercial basis and outside any business activity. If the law of the country where you habitually reside nevertheless gives you protection that cannot be excluded by contract, the choice of Polish law does not take it away.