I'll respond to several concerns raised here (as a PartsBox founder):
I know the current paid plans are way too expensive for hobbyists: they only make sense for companies. Regarding features, I would love to be able to offer everything for free, but I do have to make a living. Even as it is now, there are plenty of companies using the free hobbyist/maker plan. If I move even more features from the paid plans to the free plan, I won't be able to sustain PartsBox.
As for EAGLE import, it was left out from the free version because EAGLE is pretty much commercial (and fairly expensive) software at this point.
Regarding cloud-based systems: I know it's a popular sentiment to hate anything that is web-based. But web-based means I can offer two important things: first, software that runs on every OS out there (and PartsBox has users on Mac OS, Linux and Windows), and second, real-time updates which are not appreciated by single hobbyists, but are a crucial feature for teams and companies working with their CMs. You always see an up-to-date version of your data, and if somebody else removes stock, you see it immediately.
As for the website going down, while I have no intention of taking it down, it's a valid concern. This is why there is an easily accessible button in Settings, that lets you download a JSON dump of everything you ever entered into PartsBox, in a machine-readable format, with a single click. Just back up your data every once in a while and you'll be fine.
The comment about using software from companies that are "well established and profitable", hmm, I can only smile (sadly). The reality is that, in general, the bigger the company looks, the sooner the software will disappear. For VC-funded companies it's because either they run out of funding, or because they get acquired (or acqui-hired) and the new owners shut the product down (google for "incredible journey startup" to see what I mean). Even giants like Google shuts things down left and right with little warning. I actually believe that small companies running a profitable business are the most stable ones, and that is exactly what I'm aiming for.
That said, I know that PartsBox isn't necessarily for everyone, fortunately there are other options, too!