If you're looking for a free and integrated product, you may like to consider Intuit Link.  It functions as a basic client portal but is somewhat limited and you have little control over its workflow as well as changes Intuit makes from time to time with no input from you.  And remember your access to data stored on the portal is only contingent upon your current subscription and Intuit may decide to archive historical data with prior notice to you, which means you should always download and backup your data regularly.

If you decide to use it, make sure you learn to use it both as an accountant and client as you will need that knowledge to help your clients diagnose issues on the fly.  Also, do a search here (although you'd be better off searching this website from Google) to find out more about questions others have raised and their usual complaints.

https://proconnect.intuit.com/community/banking/help/using-proconnect-intuit-link-in-proseries/00/53...