Windows → AndroidUSB cable or Quick Share
Cable: Unlock Android, connect a data-capable USB cable, tap the USB notification, choose File transfer, and drag files into Download or Documents.
Wireless: Install Quick Share for Windows, choose the file, select the nearby Android, and accept on the phone.
Mac → AndroidLocalSend or removable storage
Install LocalSend on both devices and use the same local network. If apps cannot be installed, copy files from the Mac to an ExFAT USB drive or microSD card, then connect that storage to Android.
Mac → iPhoneFinder, AirDrop, or LocalSend
Cable: Connect the iPhone, select it in Finder, open Files, and drag files into an app that supports File Sharing.
Wireless: Use AirDrop for Apple-to-Apple or LocalSend for the same workflow used by every platform.
Windows → iPhoneApple Devices or LocalSend
Cable: Use Apple Devices for Windows and copy into an app that supports File Sharing.
Wireless: Install LocalSend on Windows and iPhone, place both on the same local network, then send and accept.