BNF is the British National Formulary
BNF offers an app version (for IOS and iPadOS and Android - might also work on MacOS, if you have an Apple Silicon processor) which is available without charge. (This might be restricted to the UK.) It includes the BNF for Children, Dental Practitioner’s Formulary, the Nurse Practitioner’s Formulary and others features.
It has an interactions checker, summaries of medicines by medical area, details of medical devices, and much else.
You need to be aware that it is over 250 megabytes which might be more than you wish to allow if your device has limited capacity, or if you need to be concerned about data transfer volumes. It should also update about every month.
Traditionally, BNF have used cover colour to help its users easily identify editions. The teal-like colour I found might change every month - or not!
From a quick look, it appears to have more or less the same content as the paper version or the website.
9th March 2020
I have just had confirmation from the developers of the space needed:
I'm told for iOS and Ipad 285MB and 14.5MB for Android devices free space should be enough.
A surprisingly large difference! Luckily, I have plenty of space on the devices I use - but it could be too much for quite a few members. (My previous phone would have told me to get lost, it was so tight on space.)