atlassian is the big one - jira actually beat out basecamp (and fogbugz), despite them being quite similar at the beginning, and ousted the incumbent that is ibm rational suite and their ilk.

They did it by one simple trick - becoming the first ones who offered free license for open-sourcers. They invented this idea. After that, they needed to do nothing more, almost automatically becoming a monopoly. I was there working for one of the early competitors who was thrown in the dust by that decision of Atlassian and was too late to realise they had to do the same - and folded two years later.

This is also the stated rationale for Cloudflare’s generous free tier. They build loyalty with hobby and side projects, and engineers take that familiarity to work with them.

DigitalOcean also had a strategy of going after the little guys/early phases of companies with their 5$ offering and lots of good free material/tutorials.

yes, Slack and github strategy. After Slack got big, it shrunk what it provides for open-source communities though. So, expect Cloudflare eventually switch.