Taskwarrior is a free, open-source to-do list manager for the command line. It is meant for users who want to manage tasks quickly without a graphical interface, and it is released under the MIT licence. Taskwarrior is software you install on your own computer; the project does not run a hosted service.
According to its GitHub page the project is the work of a small group of volunteers and has been in development since 2006. It sits under the Gothenburg Bit Factory GitHub organisation; no company seat or parent company is named. Tasks are kept in a local database. To sync between devices, Taskwarrior 3 uses TaskChampion: you can run your own TaskChampion sync server or use storage at cloud providers such as AWS S3 or Google Cloud Storage. With self-hosting you decide where the data lives; with cloud storage the jurisdiction depends on the provider and the region you choose. For European organisations this means full control over data and syncing, but no vendor support behind it.