GasCheck — Privacy Policy

Effective: 11 August 2026 · Last updated: 11 August 2026

The short version. GasCheck reads your location to rank nearby fuel stations, and that location never leaves your phone. The app downloads the whole national price list published by government open-data services and does the ranking on your device, so no server is ever told where you are or which station you chose.

There is no account, no sign-up, no analytics, and no crash reporting. GasCheck shows one advertising banner, served by Google AdMob, which is the only third party that receives anything identifying about your device.

1. Who is responsible

GasCheck is an independent app published by Celso Madeira, who is the data controller for the purposes of the EU General Data Protection Regulation (GDPR).

Contact: privacy@karmakai.pt

2. Your location

With your permission, GasCheck reads your device's precise location while the app is open. It is never read in the background.

Your location is used entirely on your device, to:

centre the map on where you are;
measure the distance to each station;
compute the effective price — the pump price plus the fuel burned driving there and back — and rank the results.

Your location is not sent to us, and not sent to the fuel-price sources. This is a consequence of how the app is built: it downloads the complete national dataset for your country and filters it locally, rather than asking a server "what is near this coordinate?". The servers involved therefore never receive a coordinate at all.

You can withdraw location access at any time in your device settings. The app will no longer be able to rank stations, as that is its only function.

3. What leaves your device

Connection	What the recipient receives	Why
Fuel price data `celsomadeira.pt`	Your IP address and a standard request timestamp. No location, no identifier.	To download the Portuguese price list, republished from DGEG open data. This server is operated by us and hosts the price data only.
Fuel price data `sedeaplicaciones.minetur.gob.es`	Your IP address. No location, no identifier.	To download the Spanish price list from the Ministerio para la Transición Ecológica.
Map tiles `tile.openstreetmap.org`	Your IP address and the map tiles requested, which reveal the approximate area you are viewing.	To draw the map. Served by the OpenStreetMap Foundation under their privacy policy.
Advertising Google AdMob	Advertising ID, IP address, device and ad-interaction data — see §4.	To serve the single banner that funds the app's running costs.
Navigation hand-off Google Maps, Waze, or your chosen map app	The coordinates of the station you selected — only when you tap "directions".	To start turn-by-turn navigation. That app's own privacy policy then applies.

An IP address is transmitted by any internet request and is, in principle, personal data. Requests to celsomadeira.pt may appear in ordinary web-server access logs kept by the hosting provider for security and troubleshooting. These logs are not linked to any user, not used to build profiles, and not shared.

4. Advertising

GasCheck displays one banner, at the foot of the results list, served by Google AdMob. There are no interstitials, no video, and no ads anywhere else in the app.

Consent in the EEA, the UK and Switzerland

The first time you open the results screen, Google's consent form asks whether you agree to personalised advertising. Your choice is stored on the device and honoured on every later visit; you are not asked again.

If you consent, Google may use your advertising ID and related data to personalise ads. Legal basis: your consent (GDPR Art. 6(1)(a)).
If you decline, AdMob serves limited ads, which do not read or write identifiers on your device for advertising purposes. The banner still appears; only its targeting changes.

You can change your answer at any time by resetting the advertising ID in your device settings, which clears the stored choice.

GasCheck does not ask for App Tracking Transparency permission on iOS, so iOS ads are not personalised using the IDFA.

What Google does with this data is governed by Google's Privacy Policy and Google's advertising terms. We receive only aggregate revenue totals — never any data about individual users.

5. What is stored on your device

All of the following stays on your phone. None of it is transmitted to us, and all of it is deleted when you uninstall the app.

Your settings — fuel type, consumption in L/100 km, tank size, and search radius.
A cached copy of the price list for your country, so the app works on a poor connection. Discarded automatically once it is more than 48 hours old.
Advertising diagnostics — a count of consecutive failed ad loads, used to hide the banner if ads stop loading. No identifiers.
Your advertising consent choice, stored by Google's consent SDK.

6. What GasCheck does not do

No user accounts, sign-up, email address, or password.
No analytics, telemetry, or usage tracking of any kind.
No crash-reporting service.
No background or continuous location access.
No selling or sharing of personal data. We hold no personal data to sell.
No advertising from fuel retailers or competing fuel-price apps, so the ranking cannot be influenced by an advertiser.

7. Legal bases under the GDPR

Processing	Legal basis
Reading your location on the device	Consent — the permission you grant to the app (Art. 6(1)(a)). The data never reaches us.
Server access logs containing IP addresses	Legitimate interests — operating and securing the service (Art. 6(1)(f)).
Personalised advertising	Consent, collected via Google's consent form (Art. 6(1)(a)).
Limited (non-personalised) advertising	Legitimate interests — funding a free app, without device identifiers (Art. 6(1)(f)).

8. Retention

We do not hold any personal data about you, so there is nothing for us to retain or delete on request. On-device data persists until the cache expires (48 hours for price data) or you uninstall the app. Server access logs are retained by the hosting provider for a short period for security purposes. Data held by Google in connection with advertising is retained according to Google's own policies.

9. Your rights

If you are in the EEA or the UK, you have the right to access, rectify, erase, restrict, and object to the processing of your personal data, and the right to data portability.

In practice these rights have little to act on here: GasCheck holds no account and stores nothing about you on our systems. Uninstalling the app erases everything it has kept. For data held by Google in connection with advertising, please use your Google Account controls.

You may contact us at privacy@karmakai.pt with any request or question. You also have the right to lodge a complaint with your national supervisory authority — in Portugal, the CNPD; in Spain, the AEPD.

10. Children

GasCheck is intended for drivers and is not directed at children. We do not knowingly collect personal data from children.

11. Accuracy of fuel prices

Not a privacy matter, but worth stating: prices come from official government open-data services and may be out of date or incorrect at the pump. GasCheck flags data that is no longer fresh and discards anything older than 48 hours. Always check the price displayed at the station.

12. Changes to this policy

If this policy changes materially — for example if a new data source or a new third-party service is added — the "last updated" date above will change, and significant changes will be announced in the app's release notes. The current version always lives at this address.

13. Contact

Celso Madeira
privacy@karmakai.pt