For outright reliability and true offline finding, Apple’s built-in Find My is far and away your best bet. Its Offline Finding network leverages hundreds of millions of iPhones, iPads and Macs around you to locate a lost device even when it’s powered off or has no cell signal—just be sure Settings > [Your Name] > Find My > Find My iPhone has both “Find My network” and “Send Last Location” turned on.
That said, here are a few other routes:
• Prey Anti-Theft (iOS/Android) – cross-platform, stealth mode, remote lock/wipe. You still need some data connection to update location.
• Life360 (iOS/Android) – great for family circles, real-time sharing. Again, online only.
• Bluetooth trackers (Tile, Chipolo) or even slip an AirTag into your phone case – these leverage their own crowd-sourced networks to ping you if your phone’s offline or dead.
iOS vs. Android: Android’s Find My Device works, but it’s a bit hit-or-miss outside major metros and doesn’t have the same privacy-focused, peer-to-peer offline network that Apple’s built in. With Apple’s ecosystem you get seamless, encrypted locating without worrying your data’s being hoovered up.