Open-source GPL software for trust! SSHelper provides SSH login to your phone, SFTP, SSHfs and also rsync (not working on Android 4.x) capabilities (e.g., transfer files from/to phone, also perfect for backups). Authentication supports password and public keys. Write access to external SD card (Android 4.4+) possible with some tricks (no need to root phone).
Excellent - a must-have utility which has saved my bacon more than once. If you're ever in Barcelona, Mr. Lutus, I owe you a couple of pints!
Does not allow renaming files via sftp. So I end up with *.part files because my file manager cannot rename them after finishing copying them to the phone. This ruined usability for me. Another issue, is that I had to disable persistent annoying notification by blocking it. It would be better if the application had a setting to not show notification at all so user who do not want to see it could just turn it off in the app settings. But since this annoyance has a workaround, it is not as important as the first issue.
Tried to login and scp a file to my desktop - it just worked out of the box. This is much more useful than the crappy MTP Android suggests to use.
Up and running with SSH under PCManFM (Linux file manager) and command line SFTP in just a couple of minutes (after much frustration with other apps). Thank you.
All developers should use this application as a guide on how to code without advertising, fees, bloatware, clickbaits, donations... This application represents the pure opensource community. Thank you so much for your amazing work.
07.23.2017 Version 9.0. Reluctantly gave up on the idea of creating an rsync binary that will work on all Android versions and kernels. Returned to rsync version 3.1.2, the most recent version at the time of writing. This rsync binary will not work on all Android devices, but it will work on the majority of them. This update also addresses some important security issues.