Open Source Network Servers in Java

DrFTPD is a distributed FTP server in Java with a master and multiple file-transfer slaves. The master handles control and metadata; slaves serve data, enabling merged sites and aggregated bandwidth with standard FTP clients.

Apache MINA is a Java network application framework for building high-performance TCP, UDP, and serial I/O applications. It provides an event-driven API and integration with protocols and dependency injection.

EJBCA is an open-source PKI certificate authority for issuing and managing TLS, code-signing, and identity certificates. It runs as a standalone CA or inside a JEE stack and supports custom profiles and hardware security modules.

JGroups is a toolkit for reliable group communication in Java. It provides channels, membership, and messaging over UDP, TCP, or TUNNEL so applications can build clusters, replicate state, and coordinate without IP multicast.

Netty is an asynchronous event-driven network framework for building high-performance TCP/UDP servers and clients in Java. It provides a unified NIO API, flexible event model, and SSL/TLS support; the project succeeded the earlier Netty 2 line.

Apache James is a Java mail server platform that implements SMTP, IMAP, POP3, and related mail-processing components. It provides modular server runtimes, mailet-based message processing, and multiple storage backends for enterprise and custom email infrastructure deployments.

JPPF is a grid computing framework for parallelizing Java applications across many machines. Jobs are split into tasks, a server distributes them to nodes, and results are aggregated; no shared filesystem is required.

Verax IPMI is a Java library implementing IPMI 2. 0 over UDP for hardware management. It provides asynchronous session handling, RAKP/AES encryption, and encoders for sensors, events, and FRU data.

Java SOCKS server implementing SOCKS4 and SOCKS5 for proxying TCP connections; runs on the JVM and can be used as a standalone proxy or embedded component.

ApacheDS is an embeddable Java directory server that implements LDAPv3 and includes integrated directory-service capabilities for identity use cases. It provides extensible schema handling, authentication components, and directory data services for JVM applications and standalone deployment.

Java Sockets is a class library that wraps Java NIO (java. nio. *) in a C++-style sockets API for non-blocking network I/O on the JVM.

Coadunation is a Java server platform designed to run web applications and daemon-style services in a unified runtime environment. The project includes infrastructure components for application hosting, service management, and web-based administration across different operating systems.

ColoradoFTP is a Java FTP server implementation that targets RFC 959 and extension support for customizable file-transfer services. It provides a plugin-oriented architecture for extending authentication, command handling, and server behavior while running on standard JVM environments.

JCGrid is a Java-based grid computing toolkit for splitting CPU-intensive work across machines without shared filesystems. It handles task distribution, file transfer, and caching; nodes can join or leave at runtime.

Jsmtpd is a modular Java SMTP daemon with plugin support for TLS, authentication, spam detection (SpamAssassin, RBL), antivirus (ClamAV), and other filters.

QuickServer is a Java library for building multi-threaded, multi-client TCP servers. It abstracts ServerSocket and connection handling so developers can focus on application protocol logic.

xSocket is a lightweight Java NIO library for building high-performance TCP/UDP servers and clients in blocking or non-blocking mode.

jMOS is a Java library for the Media Object Server (MOS) protocol used between newsroom systems and media servers. It supports MOS 2. 8.