Some of these "open source" options are not really open source.

- Outline uses the Business Source License 1.1, which eventually becomes open source (Apache 2) four years after each release. https://github.com/outline/outline/blob/main/LICENSE

- Invoice Ninja uses Elastic License 2.0 (ELv2), which allows you to host it for yourself, but not for other people. https://github.com/invoiceninja/invoiceninja/blob/master/LIC...

Source code available is not the same thing as open source.