Mendeley is freely available as:
Access to mobile apps. Please note, the mobile apps available for Android and iOS devices will be discontinued and removed from the App Store and Play Store on March 15 2021. If you are using the mobile apps, please ensure that you sync your library to the cloud before this date so you can continue to access your references in using the desktop or web version of Mendeley.
Your Mendeley library can be synchronised across platforms, so you can access your Mendeley library from any device.
With the free version you have 2GB of personal storage space. It is possible to pay for a premium plan which gives you more storage space.
Please note that Mendeley is not accessible to screen readers. If you use a screen reader you might prefer to use EndNote or Zotero instead.
Mendeley is currently developing a new service, called Mendeley Reference Manager, which is currently in beta. This blog post from Mendeley addresses the rationale behind the change.
This Guide covers only Mendeley Desktop and Mendeley Web, which will continue to be available until further notice. We will develop support for the new Mendeley Reference Manager when it is fully adopted.
Mendeley have guidance on the new services:
A free Mendeley account gives you
To see how much storage you have left: