URL actions can be used to control almost anything with an HTTP based API, from Raspberry Pi to Philips Hue.
This is where the URL will go, any other attributes like POST data can be set elsewhere. Any variables added to the URL here will be treated as GET variables.
Here you can specify any extra data that needs to be sent with the URL request. See below for more information.
Repeat Interval in Seconds
If you have a value in here, when you press and hold the action button on the Today Screen it will repeat with this frequency, great for actions like adjusting your television volume level.
Double Tap - Security
As there is no feedback provided to the Today Screen buttons for URL actions, couple with the fact they may be controlling security sensitive equipment such as garage doors, this option being set will require a double tap of the button on the Today Screen to avoid accidental presses.
POST/PUT - More Information
On this second screen you can choose to send your data with a POST or a PUT, simply by selecting the button with the type on it.
The data you enter here can be can be either JSON, text - plain text or form-urlencoded, or authentication credentials, in the form of username:password. Basic authentication will be attempted first, falling back to digest authentication if basic fails. JSON data will be validated for validity.