Donum is a GPS land area measuring app for Android. The user measures a field or plot in one of four ways: (1) Area — tapping corners on the map to build a polygon; (2) Distance — tapping to draw a line; (3) Point — marking a single location; (4) Walk — recording the boundary by physically walking around the plot while GPS fixes are logged. The app then shows area, perimeter and edge lengths, converting between m², hectare, dönüm, km², acre, square foot, square yard and square mile. Measurements can be saved as named plots with an optional note and colour, and exported as GeoJSON, KML, GPX, CSV or a printable PDF report. The map is rendered by the app's own canvas tile engine using OpenStreetMap raster tiles (standard, OpenTopoMap and a high-contrast layer). Area is computed with a spherical excess formula on the device — no measurement or calculation is sent anywhere. Monetization: a single auto-renewing subscription, "Donum PRO", sold through Google Play Billing with a 3-day free trial followed by a weekly charge. PRO unlocks walk measuring, unlimited saved plots (free tier is capped at 5), KML/GeoJSON/GPX export, the PDF report, the topographic and high-contrast map layers, and plot colours and notes. There are NO advertisements and NO advertising SDKs of any kind. There are no user accounts, no sign-in, no registration and no cloud sync. Everything the user creates lives in the browser storage of the app on their own device and is deleted when the app is uninstalled. Permissions used: ACCESS_FINE_LOCATION and ACCESS_COARSE_LOCATION (to show the user's position and to record the boundary in Walk mode), INTERNET (only to download map tiles from OpenStreetMap tile servers and to talk to Google Play Billing). Honesty note that must be reflected in the terms: Donum is a consumer GPS tool, not a surveying instrument. Phone GPS typically drifts 3-10 metres. Results are NOT an official cadastral survey and must not be relied on for title deeds, boundary disputes or any legal proceeding. The app must not be presented as a substitute for a licensed surveyor.