No. Currently Keepmark is a desktop application only. However, documents are stored in a user-accessible form and can be synchronized with mobile devices, e.g., using services like Drobox or the WebDav protocol.
Unlike most currently available services, Keepmark does not store your files on their servers. The data is yours and it is up to you to decide if you want to store it in the cloud and which one to choose.
If you want to create notes on your phone you can use one of the markdown editors available for your phone (e.g. Markor for Android) and store the files in a folder syncronized with Keepmark.
However, I do not exclude that in the future there could be a mobile application that would make it easier to work with documents on such devices.