EndNote is available as:
You can use them independently, or synchronise them so you can work with your EndNote references from any device: your own computer, on the Web or on your iPad. The online and iPad versions do not have all the functionality of EndNote Desktop.
EndNote libraries created in version 20 are not backwardly compatible with older versions of EndNote because Clarivate introduced a new database engine from X9.3 onwards. When you use EndNote X9.3 or 20 to open a library that was created in an earlier version, you will be prompted to create a new converted library.