[eknkc]

- Varnish comes to my mind. Has Varnish Plus with paid features. - There's GitLab with CE and EE editions. - Elasticsearch has a similar approach I think. - As you mentioned, there is MongoDB, NGINX etc.

I think this is a reasonable model. It's not easy to build / sustain complex software and while it works for a lot of projects, maybe majority of projects get neglected or depends on a few dedicated contributors. Who often burns out etc.

It also provides some confidence to users (at least to me). I know the project is open source. If the backing company goes evil, a fork can always emerge (iojs comes to mind). And I also know that some people are making money over this software and they will keep it alive / work on it as long as it sustains the business.