Excluding contributed tasks
You can use any of the previous filters for the /api/task endpoint and add the following argument: participated=1 to remove from the results, the tasks that the user has participated in. In this way, you will be entirely in charge of how the tasks are presented to your users. You will design how they will be delivered.
This endpoint now accepts as well the external_uid parameter, as by default it identifies authenticated users, as well as anonymous users. If you are using the external UID, include it.