ISPConfig

ISPConfig is a free, open-source hosting control panel for Linux that provides web-based management of websites, email, DNS, databases, FTP, and more. It is one of the most popular free alternatives to commercial panels like cPanel and Plesk, particularly in European hosting markets.

The panel supports Apache and Nginx as web servers, BIND and PowerDNS for DNS, Postfix and Dovecot for email, PureFTPd for FTP, and MySQL/MariaDB for databases. Let's Encrypt integration provides automatic free SSL certificates for all hosted domains.

ISPConfig's standout feature is its multi-server architecture. A single ISPConfig installation can manage multiple servers, distributing web hosting, mail hosting, DNS, and database services across different physical or virtual machines. This allows hosting providers to scale by adding specialized servers (a dedicated mail server, a dedicated database server) without running separate control panel instances.

The interface provides three access levels: Administrator (full server management), Reseller (can create clients and allocate resources), and Client (manages their own websites, email, and databases). This multi-tier access model supports standard hosting business structures without additional software.

ISPConfig includes a built-in migration tool for importing accounts from other panels, though the process is less automated than cPanel's Transfer Tool. DNS cluster support allows running redundant nameservers that automatically sync zones from the master ISPConfig installation.

The community around ISPConfig is active, with extensive documentation, forums, and third-party plugins. The project has been actively developed since 2005, making it one of the longest-running open-source hosting panels. While it lacks the polish and ecosystem of cPanel, the zero licensing cost makes it attractive for hosting startups and providers with tight budgets.