LocalSend is a free, open source app for sharing files between devices on the same network. It was first released in 2022.
It works like AirDrop but across every platform: Windows, Mac, Linux, Android and iPhone. Devices on the same Wi-Fi find each other automatically, and files, folders and text are sent straight between them with encryption. No account, cloud server or internet connection is needed, so files never leave the local network.
LocalSend is completely free with no ads, and the code is public on GitHub.