Onavo Extend

Using your phone during a cruise can lead to nasty surprises on your bill afterward due to international digital roaming charges. This app cuts those data rates by up to 80 percent. You’ll be able to monitor the bandwidth used by every app on your phone while compressing the data that you do download over 3G, EDGE, and LTE with tricks such as not loading web images until you scroll down to them — you won’t pay for pictures you don’t see. You’ll be able to turn off the worst unnecessary data hogs and make your necessary apps a little less costly. The service automatically shuts off when you connect to Wi-Fi. Free for iOS and Android devices. onavo.com