LocalSend

LocalSend moves files and messages between devices on the same local network, so nothing is uploaded to a service in between and no internet connection is needed. Among open-source stand-ins for AirDrop it is the one that is not tied to a single vendor's hardware, and one Flutter codebase covers desktop and mobile. Volunteers translate it through Weblate, and it is packaged across a long list of distributions. Apache-2.0, and past 87,000 stars on GitHub.