Permissioned access to Outlook, OneDrive and Teams via the user's own Microsoft account
Free
2 servers across productivity & workflow. The largest is Microsoft 365.
Productivity & Workflow
Permissioned access to Outlook, OneDrive and Teams via the user's own Microsoft account
Permissioned access to Gmail, Drive and Calendar via the user's own Google account
The rest either hold an API key issued by the publisher or ask for nothing.
Listed without a verification tick. Read the listing before installing.