Tool that watches files / folders and upload on change on OS X?

I am looking for an SFTP or rsync (?) tool (or script?) that watches a certain folder or certain files and uploads them to a remote server securely on change. The background: I've been using Sublime SFTP for that, it works quite well, but sometimes "forgets" its watching duties. Also, I'm giving Atom a go as an alternative editor and there are no tools that live up 100% to Sublime SFTP. Most editor-based SFTP tools just upload files upon save, but that doesn't cover files built buy gulp or CodeKit. We've been adding gulp-sftp to our build scripts, but that also has drawbacks. So what I've been wondering: isn't there a standalone application that simply can watch files or folders for changes and upload them via SFTP, rsync or scp?