Apprise
Apprise - Push Notifications that work with just about every platform!
...There is a small built-in Configuration Manager that can be optionally accessed through your web browser allowing you to create and save as many configurations as you'd like. Each configuration is differentiated by a unique {KEY} that you decide on. Once you've saved your configuration, you'll be able to use the Notification tab to send you're messages to one or more of the services you defined in your configuration. You can use the tag all to notify all of your services regardless of what tag had otherwise been assigned to them. At the end of the day, the GUI just simply offers a user friendly interface to the same API developers can directly interface with if they wish to.