have a nifty API and developers have used this to create all sorts of apps and services.
Agile is the plan which charges for electricity in half-hour chunks throughout each day and the API allows actions to be taken depending on the prices. For example, a smart plug on my dishwasher switches on at the cheapest 2-hour slot during the night and the washing machine is only active between 1:30pm and 4pm (the cheapest day slots)
You can make IFTTT applets which utilise this API (or use existing IFTTT applets) which do things too. For a laugh, I placed a Hue bulb on top of the large plushy and had IFTTT turn it Green (OK to use kitchen appliances) or Red (don’t bother doing anything in the kitchen) - depending on the prices at the time. There are also external apps which log your consumption and can warn of upcoming good/bad periods up to 48 hours in advance with further predictions in some cases.
There are alternatives, but I’ve found to be very good so far. I’ve been with them for 2+ years and tried various plans. I’m now using Agile and still liking their services. They are pushing the boundries of the normally boring, but expensive and strangely mysterious utilities sector.