I started https://ipinfo.io as a side project, and then ran it fulltime as a one-person SaaS app for over a year. We're now a team of 8, profitable, and growing quickly. We're still 100% bootstrapped, and I have zero plans to raise any outside funding.

We started with a simple IP geolocation API, which now handles over 20 billion API requests per month. We've added new data to that service, such as IP type classification (hosting, isp, or business, and soon education too), IP to company, and carrier detection. And we've also launched some other products, like hosted domain API (all domains hosted on an IP, sometimes called reverse IP), IP ranges belonging to an organization, and an ASN API. We've got a lot in the pipeline too, including some domain related offerings (see https://host.io for an early preview).

So it's definitely possible :) What sort of SaaS product are you thinking of launching? Would be happy to chat! Shoot me an email at ben@ipinfo.io