Just came across the excellent FREE software “InfiniteWP” via a Yoast post on Facebook. I’ve got WordPress Service Contracts setup with some web design clients of mine whereby for a small yearly fee I keep their core WordPress systems and installed plugins up to date. This helps keep their sites secure, fast and modern. Previously, I would have had a plugin on their sites that notified me via email whenever there was a new version of WordPress or any of the plugins installed on a site and I’d have to go login and upgrade or sometimes manually upgrade via FTP. With 24 sites (currently) to manage that turns into a fair bit of work.
Installing InfiniteWP (as a PHP application on my own local server) and adding my clients sites to it now enables me to bulk update plugins, themes and WordPress core from one location right on my own PC in pretty much 1 click! The system requires the InfiniteWP Client plugin to be installed on all sites too which is a bit of hassle but only needs to be done once to create the connection.
The software also handles Backups, Groups and other functionality via paid add-ons..