The newly redesigned EndNote Web allows you to sync your library across your devices, from online, desktop, to iOS devices. It is exclusively available to EndNote 21 customers for 3 years, with unlimited storage for full-text documents, file attachments, and an unlimited number of references.
*NOTE: To enable sync from your EndNote 21: Click on Edit > Preferences> Sync > Enable Sync. Then click Sign up to login or to create an account.