IFTTT stands for If This Then That and gives you a very powerful way of controlling other devices in your smart home by setting up Applets which are simply groups of instructions to carry out an action if something happens or changes.
So for example, If my Boundary Alarm is Triggered Then Flash my Phillips Hue lights
This is a very basic example but there really is no limit to the combinations of commands you could use.
The IFTTT service can be found at ifttt.com and is available in two flavours, a free service and a premium subscription. Boundary will work with either the free plan or the subscription service, you can find out more about the differences in the plans here: https://ifttt.com/plans