Turtl is an encrypted, collaborative note-taking app for organising bookmarks, passwords, files and lists. Notes are kept in Spaces, can be searched by text or tags and written in Markdown. They sync across devices and can be shared selectively with colleagues or family. You can use the hosted premium service or run your own Turtl server at home or at work.
The source code is public on GitHub: the apps are licensed under GPL-3.0 and the server under AGPL-3.0. The hosted service is offered under the name Lyon Bros LLC; the GitHub organisation lists San Francisco and the privacy policy refers to US court orders, so the provider is American. The provider does not state where hosted data is stored; according to the privacy policy, data remains encrypted on the service. Organisations that want full control over jurisdiction and location can host the open-source server themselves in Europe, for example with a European cloud provider. Development has slowed in recent years, which is a point of attention for long-term business use.