OpenSignal is an award-winning app, packed with features to help you accurately measure your everyday experience on your mobile network. It includes download speed, upload speed and latency test, test speeds on cellular or wifi. It also retains a history of speed tests, visualised on a map or list.
The speed test allows you to find out the location at which the signal is strongest and also compare cellular and wifi speeds. Network availability and speed stats are stored and listed, based on your own experience as well as the experiences of others—whether of your own service-provider or on other networks.
Coverage maps are available for all operators and zoom in to street level. The coverage maps are based on the signal experienced by users. The data is collected by crowd-sourcing and is fairly representative. You could use this information to download maps before visiting areas with weak or no signal.
Overall, a very useful tool to understand your mobile connectivity efficiency.