GoJS – Interactive JavaScript Diagrams for the Web

As one of the developers working on yFiles, another commercial solution in the same space I feel the problem of competing against "free". There's also relatively few useful feature subsets that can be licensed separately for a smaller price. But we also regularly get questions what days is apart from D3 which is a lot cheaper (in visible monetary terms at least).

It's not so much that you're competing with free, it's that you're competing with open source (which is also often free). The nature of open source is that it's very often better in terms of both quality and community. Add in the overhead of acquisition, and it makes it a no-brainer.

It's very hard to tell ahead of time that a paid library is going to save you X programmer days. You'd really need some way to convince someone that you are best-in-class in documentation, in community, in stackoverflow answers, in plugins, in features, in customizability, in debuggability, before they even start the painful and lengthy requisition process. And dedicated support is nice, but is it better than being able to google the answer to every question?

Now of course if you pick a small niche and no strong competitor exists, great, it's pretty easy to become best-in-class with your thousands of hours. But pick anything that is used by FAANG, and now on top of the community contributors you've got dedicated engineers they've assigned to invest in their investment.