Adding a board user is ideal when you want to involve someone outside of your workspace in a specific project or board. Whether it's a client you're working with, a freelancer you've hired, or a partner you're collaborating with, inviting them as a board user allows them to contribute to a specific board without accessing your entire workspace.
Board users are best when someone needs authenticated, direct access to a specific board.
On current paid plans, board users are unlimited and do not add an extra per-user charge. Legacy plans and custom or Enterprise contracts may define board-user limits or costs differently, so check your workspace plan details if you are unsure.
When board users count toward seat quantity under an eligible fixed-member or per-member arrangement, adding seats creates an immediate prorated charge, and reducing seats creates an immediate prorated credit. For more about invoice line items and proration timing, see How does prorated billing work at Air?
If a collaborator only needs to view, download, or review content, use a share link instead. For external viewing or download without an account, see Does someone need to create an Air account to see content I share with them? If someone needs to submit or upload content without broader access, consider content collection forms.