Zapmap as said. However, I also find the Electroverse app from Octopus really good. You don’t have to be an octopus customer and you can create an account and get an RFI card from them which works with lots of different partners chargers. Very handy when you’re travelling and can’t find a contactless charger nearby. You can start the charge within the app as well but I’ve had places where app connection goes astray and glad to have been able to just tap the provided RFI card!