Anyone know how to find a list of small b2b SaaS companies?

I've been trying to use ReferenceUSA to find a list of b2b SaaS companies. I know the list on Indie Hackers is nice, but I'd like to go beyond that. I've been trying to search for b2b SaaS companies with ReferenceUSA, but I haven't found a good way to narrow down the search to just those via their SIC or NAICS code.