Flynn is entirely open source and BSD-licensed (https://github.com/flynn/flynn). You can run Flynn on any infrastructure without paying us anything.
The price you reference is for our Managed Flynn product, where we act as your ops team, operating a Flynn cluster for you and providing hands-on support for your apps and databases in production.
I know it's probably not as feature-complete as those other PaaS's, but it would be great to get it at a glance.
Many people who choose Flynn are not directly comparing us to hosted platforms, as they want more control over their infrastructure (where they run it, lock-in avoidance, etc).
As far as individual features go, we are closest to Heroku (and maintain buildpack/runtime compatibility). However there are differences including our support for other databases (MySQL and MongoDB in addition to Postgres and Redis) and many other smaller things like HTTP/2 support.
I am also curious to find out what is the running cost for maintaining flynn. Is there one dedicated engineer minitoring the infra?
We do have a dedicated engineer managing / monitoring our infrastructure. It's not a set-it-and-forget-it kind of thing, so if you don't have somebody to manage your infrastructure, the hosted version might be a better choice.
The big cost savings win was for all of our /other/ engineers who now don't need to know anything about ops to get their apps running. Previously with Chef, everybody was responsible for writing recipes and setting up environments, but now we have a standard set of buildpacks that work with our apps, and when we need to transfer an app to a client (as we're a dev agency), we can set it up on Heroku and it should "just work".
- Small and side projects run well without supervision.
- Existing ops teams can manage Flynn without much additional effort.
- Medium sized teams that don't want an internal ops team pay us for Managed Flynn where we take over all ops-related responsibilities.