- [389 Directory Server](https://www.port389.org/) - Enterprise-class Open Source LDAP server for Linux. ([Source Code](https://github.com/389ds/389-ds-base))
- [Apache Directory Server](https://directory.apache.org/apacheds/) - Extensible and embeddable directory server, certified LDAPv3 compatible, with Kerberos 5 and Change Password Protocol support, triggers, stored procedures, queues and views. ([Source Code](https://github.com/apache/directory-server)) `Java`
- [FreeIPA](https://www.freeipa.org/) - Integrated security information management solution combining Linux (Fedora), 389 Directory Server, Kerberos, NTP, DNS, and Dogtag Certificate System (web interface and command-line administration tools). ([Source Code](https://pagure.io/freeipa))
- [FreeRADIUS](https://freeradius.org/) - Multi-protocol policy server (radiusd) that implements RADIUS, DHCP, BFD, and ARP and associated client/PAM library/Apache module.
- [FreeRADIUS](https://freeradius.org/) - Multi-protocol policy server (radiusd) that implements RADIUS, DHCP, BFD, and ARP and associated client/PAM library/Apache module. ([Source Code](https://github.com/FreeRADIUS/freeradius-server))
- [lldap](https://github.com/nitnelave/lldap) - Light (simplified) LDAP implementation with a simple, intuitive web interface and GraphQL support. `GPL-3.0``Rust`
- [OpenLDAP](https://www.openldap.org/) - Open-source implementation of the Lightweight Directory Access Protocol (server, libraries and clients).