The app includes best-buy mortgage rates and a suite of mortgage calculators to help borrowers calculate the monthly cost of their mortgage, the impact of rate changes and the effect of overpaying.
It also incorporates the L&C one minute mortgage check which provides a quick diagnosis of whether borrowers could save money on their mortgage. Users can save details of their existing mortgage deal. They also have access to the L&C blog.
David Hollingworth of London & Country said: "This application provides a wealth of information and easy to use mortgage tools, putting it all at our customers' fingertips."