Do you need pay equity software under 100 employees?

Usually not yet. Below roughly 50 employees most comparison groups are too small for a statistical model to produce a reliable result, and the lowest published size floor of any vendor is PayAnalytics, whose own FAQ says around 50 people are needed to use the software fully. Between 50 and a few hundred employees a tool starts to earn its place, and the vendors whose own sites say they serve that range are PayAnalytics, HiBob, Figures, Ravio, Affirmity and Sysarb. Before buying anything, define job levels and pay ranges, because without them a gap analysis has nothing meaningful to group people on.