There is no best client portal software in the abstract, because a portal is only ever the front of something else. Behind every login sits a record: the client, their documents, their status, their history. A portal that has nothing behind it is a shared folder with a password, and a record with no portal is a filing cabinet the client has to phone you to open. So the shortlist is not judged on features. It is judged on four questions about the thing behind the login, and any product that cannot answer all four in a demo is answering none of them.
Who is the portal actually for
The word client hides two products. One is for the practice, so staff can see everything about everybody in one place. The other is for the client, so one person sees exactly their own things and nothing else. Most tools do the first well and bolt the second on afterwards, which is why so many portals show the client a stripped copy of an internal screen. Ask to see the client's view first, before the admin view, and judge the product on the half it treats as an afterthought.
What the portal holds, and where that lives
A portal that stores files is a different product from one that shows a record. The first gives you folders and an upload button. The second gives you a client who has a status, an owner, a start date, an onboarding that is part done, documents attached to all of it, and a history you can read backwards. Decide which you need before you compare pricing pages, because the two are priced as if they were the same thing and they are not.
Whose brand the client sees, and what leaves with you
Your client is looking at software you chose. If the vendor's logo is on it, you have introduced your client to a supplier for free. White labelling is not vanity here, it is the difference between your practice looking organised and your practice looking outsourced. The other end of the same question is export. Ask what a full export contains, in what format, and how you get it on the day you cancel rather than the day you ask nicely.
Questions people ask about best client portal software
Is the best client portal software always the one with the most features?
No. Portals fail on adoption, not on features. The client who cannot find the upload button in ten seconds emails you the file instead, and the portal has cost you a subscription and saved you nothing. Judge the shortest path a client takes from the invitation email to the thing they came for.
Should the portal be part of the same product that keeps the client record?
It is far easier if it is. Two products means two lists of clients, and two lists of clients means one of them is wrong. If you do run a separate portal, decide which system is the master record and never let the other one be edited directly.
What should a portal never do?
It should never be the only copy of anything. Treat it as a window onto a record you hold, not the cupboard the record lives in, and make sure an export gives you everything back in a format you can open without the vendor.