Stud Finder is a full version iPhone app developed by Hanja Devi that uses the magnetometer to detect hidden studs in walls. This app is perfect for those who need to hang shelves, cabinets, or other heavy objects on the wall. It can quickly detect wood studs hidden under walls, drywall, plasterboard, or stucco.

The app is easy to use. Simply place your iPhone near the wall, and the app will measure the magnetic field to detect the studs. However, the performance of the app is limited by the construction of the wall, the presence of a phone cover, and/or the material of the nails in the studs. Therefore, it is recommended to remove any external case before using the app.

Overall, Stud Finder is a useful app for those who need to detect hidden studs in walls. It is easy to use and can save a lot of time and effort. However, users should keep in mind the limitations of the app and use it accordingly.