You can use both tools at the same time
You can share Zotero libraries with colleagues who use Endnote and vice versa
Both managers can read&write a standard citation style format RIS
Moving Zotero library to EndNote:
1. To save your Zotero library, click "File" and choose "Export Library." Choose RIS as the file type and pick a filename.
2. To import your Zotero library to EndNote, click "File" and then "Import." Click the "Choose File" button and select the file you just exported from Zotero. Set Import Option to "Reference Manager (RIS)" and click Import
Moving Endnote library to Zotero:
1. To export your EndNote library for use in Zotero, click "File" and then "Export." Set the output style to "RefMan (RIS) Export" and save it as a text file.
2. In Zotero, click "File" and choose "Import." The new references will be added to a collection named "Imported" followed by the date and time.
Zotero can directly import from an online Mendeley library. Due to changes by Mendeley, it's not possible to import from a local Mendeley installation on your computer.
To import your Mendeley library, follow these steps:
Make sure that all data and files have been synced to Mendeley servers.
If you use Mendeley Desktop, check your sync settings to make sure that data and files are being synced, and confirm that you can open PDFs in your online Mendeley library.
If you use Mendeley Reference Manager, your data and files are already all online.
Make sure you're running Zotero 6, which contains the latest version of the importer as well as a new PDF reader that can display PDF annotations imported from Mendeley.
Go to File → Import within Zotero and choose the “Mendeley Reference Manager (online import)” option.
You'll be asked to log in to Mendeley to allow Zotero to perform the import. Your Mendeley password is never seen or stored.