A free program for Android, by Subway Maps by LithoByte Co..

The London tube map (called the underground), as well as public transportation/transportation maps, are all available offline. Zoom in and out and move around. It’s quick, simple, and always there when you need it. This software is fantastic for both tourists to London and long-term residents.

Includes a complete set of maps from the official TfL sources for the London tube/underground, bus, overground, TfL rail, DLR, national rail, tram, and river – basically all transit types.

There’s no need for an internet connection. The maps featured in the app are Metro/Tube, Bus, Surface, Tube for the Night, Thameslink Rail, DLR, National Railroad Administration, Tram, and River.