OpenLDAP Software is an open source implementation of the Lightweight Directory Access Protocol.

High-performance, highly scalable directory for enterprise and carrier-grade environments.

Novell eDirectory is a Lightweight Directory Access Protocol (LDAP)-enabled, directory-based identity management system that centralizes the management of user identities, access privileges and other network resources.

Commercial LDAP server. Includes overview and technical information.

A standards-based LDAP directory which leverages the scalability, high availability and security features of an Oracle database.

M-Vault is a high-performance LDAP Directory Server, including replication, high functionality access control and security management, graphical administration tools, and Web access.

Offer virtual directory (featuring LDAP support), identity management and single sign-on solutions.

Gateway software for integrating LDAP in an NIS infrastructure

RadiantOne is a flexible identity infrastructure designed to integrate identities and match them to application requirements. By virtualizing the directory service, identity infrastructure doesn't have to be one-size-fits all.