Uncovering the Best Apache Geronimo Alternatives for Your Enterprise Applications
Apache Geronimo, a Java EE 5-certified application server, has long served as a robust framework for web and enterprise applications. Built upon Sun's Java EE platform specification, its goal was to unify the best open-source components into a server runtime. However, as technology evolves, developers and system administrators often seek out new, more feature-rich, or specialized alternatives. If you're looking for an Apache Geronimo alternative, you've come to the right place.
Top Apache Geronimo Alternatives
Whether you're seeking a Java EE-compliant server with advanced features, an open-source solution, or something tailored for specific development needs, there are many excellent choices available. Let's explore some of the leading contenders that can serve as a powerful replacement for Apache Geronimo.

JBoss
JBoss, Red Hat's Java EE 5-compliant (and soon Java EE 6-compliant) application server, is a strong Apache Geronimo alternative. It offers dual licensing as an open-source community edition or a commercially supported version. Available for Free, Open Source, Mac, Windows, and Linux, JBoss provides extensive features for Web Development, making it a versatile choice for many enterprise applications.

Glassfish
GlassFish v3, developed by the GlassFish community, is another excellent Apache Geronimo alternative, notably being the first compatible implementation of the Java EE 6 platform specification. This Free, Open Source application server is available across Mac, Windows, and Linux, providing a robust and community-driven solution for Java EE development.

Oracle Weblogic Server
Oracle WebLogic Server 12c stands out as a leading Apache Geronimo alternative, recognized as a top application server for both conventional and cloud environments. Offering extreme cloud performance, scalability, and elasticity, it's available as Free Personal software for Mac, Windows, and Linux users, making it a powerful choice for demanding enterprise needs.

appserver.io
For those looking beyond Java, appserver.io presents a unique Apache Geronimo alternative as a multithreaded application server for PHP, written entirely in PHP. This Free, Open Source, and Self-Hosted solution supports Mac, Windows, and Linux, offering real multi-threading in PHP and useful services for developers, including Timer, Web Development, and Web Server features.

WebSphere Application Server
WebSphere Application Server from IBM is a Commercial Apache Geronimo alternative, known for providing the availability and security essential for business operations while optimizing costs. Available for Windows, Linux, and Java Mobile, it helps build, deploy, and manage robust and agile applications with strong Web Development features.

JOnAS
JOnAS is a leading-edge Java EE 5 certified Open Source OSGi Enterprise Server by OW2, making it a compelling Apache Geronimo alternative. Licensed under LGPL and supported by the OW2 development community, JOnAS is Free and Open Source, available for Mac, Windows, and Linux, and includes robust Web Development features.

Mako Server
The Mako Server offers a unique Apache Geronimo alternative for those working with Lua. It's an application server with an API that loosely resembles the Java Servlet API, but where server-side web applications are designed in Lua. Available as Free Personal software for Mac, Windows, and Linux, it boasts Portable and Web Development features.
Each of these Apache Geronimo alternatives brings its own strengths to the table, from Java EE compliance and robust enterprise features to open-source flexibility and niche language support. Carefully consider your project requirements, team expertise, and long-term goals to choose the best application server that aligns with your specific needs.