'Citymapper's changed my life,' says our arts and entertainment writer Jess. Whether you’re a Londoner or in the Big Smoke for a day trip, the transport system can be confusing. And time-consuming if you pick the wrong route. Thank goodness then for this clever, simple-to-use app. Wherever you want to go, it’ll tell you the quickest route, show you the transport options, costs and – rather brilliantly— how many calories you’ll burn in the process. You can set it to work or home and it has live bus, rail and tube timetables so you’ll be up to date on any disruptions to services. Also available in New York and they're planning to expand to other cities.