The data is open and stored in markdown format. Plugins are open source. The core product is not open source, but it's also just an electron app. I've always viewed Obsidian as the inverse of an open core product.

I don't really mind this way of doing it since I know that my data is "safe". I can at any time just grab my vault and open it in any editor. I can write my own editor. I can import the data into most other tools. It's when the data isn't open that I tend to avoid the product.

I see it as “open data”. Despite not being open source at its core, it apparently tries to do nothing to lock you in by holding your data in a manner you can't easily access and interpret by other means.

[caveat: it has been on my “to play with” list for a long time, but I haven't yet, so I may not know enough for my thoughts to be relevant!]

> I've always viewed Obsidian as the inverse of an open core product.

I'd like to hereby propose the "open shell" development model.

The licence method we went with for AS Notes (https://www.asnotes.io - a wikilinks and markdown based notes / docs / blog extension for VS code) was to make the client (extension) fully opensource with a public / private cryptographic licence key model, with a couple of pro gated features. I think an opensource product is very important for a notes product, where the implications of loosing access to a tool are huge for users that invest a lot of time in a knowledge base.