Most "free" stud finder apps on the app stores are not really free: they pay for themselves with ads and by harvesting your data. Ours is different. The StudFinder app is free, open-source, and ad-free, with no Google Play account required. This page explains exactly what it does, where it is honest about its limits, and how to install it.
The app uses your Android device's magnetometer (the same sensor behind the compass) to detect the metal screws and nails that fasten drywall to the wood studs in your wall. As you sweep the phone across the wall, LEDs light up in sequence when it passes over the metal fasteners, so you can mark where the stud is and drill with confidence.
That is genuinely useful for hanging shelves, mirrors, art, and curtain rods. It costs nothing, shows no ads, and makes no network connections at all - the app has no internet permission, which anyone can verify because the source code is public.
A phone only has a magnetometer. A magnetometer is accurate at detecting metal - screws, nails, pipes, and metal studs - but it cannot sense wood directly, because phones do not carry a density sensor. Dedicated electronic stud finders add a density (capacitive) sensor that reads the denser wood stud straight through the drywall, which is why they are more accurate at locating the stud itself. For heavy shelves, TV mounts, or anything structural, a physical density finder is the dependable tool. For everyday checks, the free app does the job.
Because the code is public on GitHub and rebuilt independently by F-Droid, you do not have to take our word that there are no ads or trackers. You can read the code, or simply trust that F-Droid only lists apps it has verified are free of proprietary tracking. That is a stronger guarantee than any "we respect your privacy" claim in an app-store listing.
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