Owner, member, and viewer are the only three membership roles in Tracker projects. They are separate from Account member roles. For information on how to change a project member’s role, please see Changing a project role.
Project members can create, move, delete, and edit stories, as well as add comments and attachments. Essentially, they can perform any action related to working within the project. It is not possible to restrict the actions a member can perform within a project; however, they cannot edit Project Settings, add or remove project members, or configure integrations (which are owner-specific actions).
In addition to having the same abilities as project members, project owners can add or remove members to the project from the Project Members page, edit Project Settings, and configure integrations. The owner or any admin of the account which the project belongs to can also edit project settings, add/remove members, and configure integrations for any project on the account (even those they are not explicitly members of).
Viewers are read-only members and can’t make any changes to stories, however, viewers can follow and receive notifications for any story. You can have as many viewers as you like, as they do not count against plan limits on the number of collaborators.