There is no limit to how many users you can add to your database.

We do charge extra for customers using more than the standard allotment of file storage space (currently 5 GB) and the number of emails sent per month (currently 100K), but we do not charge a "per-user" fee.

One of our main motivations for this is "What is a user?" Our databases are set up so that all employees, clients, and vendors can each be given log in access, each with their own roles-based permissions and access. How would per-user pricing work when everyone can be a user, with some accessing the system all the time and others only occasionally?

We encourage you to allow direct access to your system to those you would benefit from having direct access to it, of course restricting that access to just those things you want them to have access to.

Also, our expectation is that larger companies are going to want to us to do special customization to meet their exact needs -- so a company that would have 1,000 employees would end up paying us for that customization, and we'd make more than our standard subscription price on them.

Just as a technicality, our Terms of Service disallows someone to sell access to their Quintify database, for example as a content-based subscription site. Otherwise someone could fill up their database with good content on a particular topic and then sell login-access to the system with thousands of users. While we might offer this functionality as a new product in the future, our "unlimited users" benefit doesn't apply to users who pay to access your Quintify database.