CALs

CAL stands for Client Access License, a license that grants a user or device the right to access one or more server software products. CALs are separate from the server software license and are commonly required when software runs on a server such as Windows Server, SQL Server, Exchange, or SharePoint. The CAL itself does not license the server software; it licenses the right to access the server’s services.

There are two primary CAL models: per-user CALs and per-device CALs. A per-user CAL covers one named user to access the server from multiple devices. A per-device CAL covers a single device regardless of how many users use it. Some products also offer separate Remote Desktop Services CALs for remote connections, available in per-user or per-device formats.

Licensing and compliance: In most cases, organizations must have enough CALs to cover all users or devices that access the server, even if access is internal. CALs are typically acquired with the appropriate license terms and may be perpetual or time-limited, depending on the product and agreement. Failure to license access can expose an organization to audits and penalties. In some cloud or managed environments, CALs may be included in a subscription or handled by the service provider rather than by the customer.

Contextual note: Some Microsoft products offer alternative licensing models, such as core-based licensing, where CALs are not required if core licenses are purchased; however, for many on-premises servers, CALs remain a core concept. See also core-based licensing, remote desktop services, and server software licensing.