Very granular. When you invite someone to your team, you don't just give them "admin" or "viewer" access, you choose exactly what they can touch, category by category: Links, QR Codes, Bio Pages, Custom Splash, CTA Overlays, Tracking Pixels, Branded Domain, Campaigns/Channels, Developer API, and Export.
For most categories you can grant Create, Edit, and Delete independently, so a member could, for example, create and edit links but not delete them, while having no access to domains or the API at all. This lets you bring in freelancers, clients, or employees without ever sharing your login or giving them more control than they need.