List of the Top 15 Free Application Server Software in 2025

Linx is a robust integration platform as a service (iPaaS) designed to facilitate the connection of various data sources, systems, and applications within organizations. Renowned for its flexibility akin to programming, the platform excels in managing intricate integrations on a large scale. As a result, it has become a favored option for expanding businesses that aim to adopt a cohesive integration strategy, streamlining their processes and enhancing operational efficiency. Additionally, Linx empowers users by providing the tools necessary to customize their integrations to meet specific business needs.

RasPiEsi, recognized as the smallest open source ERP application server leveraging Epesi, operates on a Raspberry Pi Zero that features a single core and 512MB of RAM. This server is a component of the Epesi ENS, which stands as the inaugural Free and Open Source Software Enterprise Neuronal System. The Epesi BIM stack functions on the LLMP architecture, which incorporates Linux, Lighttpd, a tuned version of MariaDB, PHP 7.4 FPM, and memcached ZRAM for enhanced performance. On November 4, 2023, neofetch integrated and upgraded 77 packages for its 1.1 (Joziu) version release. RasPiEsi emerged as the smallest Epesi Node I was able to construct, demonstrating an impressive RAM utilization of merely 133MB. This compact server efficiently runs Epesi, particularly when paired with a fast SD card, and is compatible with any Raspberry Pi model—from the budget-friendly $5 RPi Zero lacking WiFi, which has 1 CPU and 512 MB RAM (used to create the disk image), to the more powerful RPi 4—without necessitating any modifications. Notably, the RPi 3 operated seamlessly as well, requiring no adjustments other than simply swapping units. The project is licensed under the MIT License, with copyright held by Janusz and Karina Tilek in 2024, ensuring its continued open accessibility for future users and developers alike.

We help businesses across various sectors speed up their software development workflows. The feature flag system is designed for clarity, enabling you to toggle features on and off whenever needed, making it suitable for user targeting, canary releases, and experimentation purposes. This flexibility empowers teams to test changes safely and efficiently.

Appwrite provides a cloud-based backend solution that streamlines the development of your backend architecture with minimal coding, allowing you to use your favorite programming languages and frameworks. This platform enables developers to focus more on innovative ideas and design elements, significantly reducing the repetitive tasks associated with backend programming. The offerings from Appwrite include: - Authentication: Over 30 login options, support for teams, user roles, and customizable labels - Databases: Continuous uptime, rapid in-memory caching, sophisticated permission frameworks, and relationship management - Storage: Secure file encryption during storage and transit, integrated image transformation features, and advanced compression options like WebP and Brotli - Functions: Seamless deployment directly from GitHub - Messaging: Support for SMS, email, and push notifications - Real-time: Unlimited subscription capabilities By leveraging Appwrite's robust features, you can save valuable time and ensure that your applications maintain stability and security for your users. Moreover, with Appwrite, your data remains entirely yours, eliminating concerns about vendor lock-in and providing peace of mind as you develop. This commitment to data ownership empowers developers to innovate without constraints.

Historically, developers have encountered a challenging choice when it comes to cloud infrastructure, torn between expensive yet inflexible platforms that often fall short in scalability and complex large-scale cloud solutions that demand considerable expertise and large operational teams. Render emerges as a perfect alternative, merging ease of use with strong capabilities and scalability, making it suitable for projects ranging from simple HTML webpages to complex applications made up of multiple microservices. This harmonious blend empowers developers to concentrate on fostering innovation without the burden of dealing with convoluted systems. By streamlining the development process, Render ultimately enhances productivity and encourages creativity in software development.

With our advanced in-memory technology combined with the application server, you can create high-performance enterprise software effortlessly, eliminating the need for custom tools or complex syntax. Starcounter applications can enhance performance by an astounding 50 to 1000 times while ensuring user-friendliness and simplicity. Development is streamlined using standard C#, LINQ, and SQL, with ACID transactions seamlessly integrated into familiar C# code. The platform fully supports Visual Studio, boasting features like IntelliSense, a robust debugger, and a performance profiler, ensuring a smooth development experience without unnecessary hurdles. By leveraging standard C# syntax and the MVVM design pattern, developers can tap into our ACID in-memory technology along with a lightweight client UI to achieve exceptional performance levels. Starcounter's technology begins providing business benefits right from the start, utilizing tried-and-true solutions that manage millions of transactions for demanding clients. This unique combination of an ACID in-memory database and an application server into one cohesive platform delivers unmatched performance, ease of use, and cost-efficiency. In essence, Starcounter equips developers with the tools necessary to create powerful applications that not only fulfill but surpass the evolving needs of modern businesses, ensuring a competitive edge in the market.

NGINX Open Source powers more than 400 million websites around the world. Building on this robust foundation, NGINX Plus functions as an all-in-one software solution that combines load balancing, web serving, and content caching capabilities. By choosing NGINX Plus over conventional hardware load balancers, businesses can explore innovative opportunities without the constraints of traditional infrastructure, resulting in savings exceeding 80% while still achieving excellent performance and reliability. This versatile platform can be deployed across various settings, which include public and private clouds, bare metal servers, virtual machines, and containerized environments. Furthermore, the built-in NGINX Plus API streamlines the completion of routine tasks, thereby boosting operational efficiency. In an era where agility is essential, today's NetOps and DevOps teams require a self-service, API-centric approach that integrates smoothly with CI/CD workflows, which not only accelerates application deployments but also enhances the management of application lifecycles. As technology continues to advance rapidly, NGINX Plus emerges as an indispensable resource for improving operational flexibility and optimizing the use of available resources. It is a pivotal asset for organizations aiming to stay competitive in a fast-paced digital world.

Internet Information Services (IIS) on Windows® Server functions as a flexible, secure, and user-friendly web server, making it ideal for diverse online hosting requirements. From media streaming to intricate web applications, IIS offers a scalable and open architecture that efficiently caters to high-demand scenarios. Additionally, its powerful features ensure smooth integration and optimal performance for a multitude of internet-based services, enhancing the overall user experience.

Concentrate on writing code while we manage every other aspect of your project. You can effortlessly launch serverless applications globally, guaranteeing exceptional performance, reliability, and scalability. No longer will you need to deal with the complexities of configuring auto-scaling or managing load balancers, nor will you face expenses for unused resources. Your incoming traffic is automatically balanced and distributed across a multitude of servers, giving you peace of mind as your code adjusts without a hitch. Each deployment taps into a network of data centers that leverage V8 isolates, which allows for swift execution times. Thanks to Cloudflare's expansive network, your applications are just milliseconds away from nearly every internet user. Start your development journey with a template tailored to your preferred programming language, enabling you to quickly create an app, function, or API. We offer a range of templates, comprehensive tutorials, and a user-friendly command-line interface to help you hit the ground running. Unlike other serverless platforms that experience cold starts during deployments or sudden spikes in traffic, our Workers run your code instantly, ensuring there are no delays. You can take advantage of the first 100,000 requests each day for free, with budget-friendly plans commencing at a mere $5 for every 10 million requests. With our service, you can devote your attention entirely to your coding aspirations while we guarantee that your applications function seamlessly and effectively. This allows you to innovate without the burden of infrastructure worries.

Lucee is recognized as the top open-source CFML application server and engine, delivering a wide range of features that include various tags and functions for web-related operations. It adeptly manages tasks such as image processing, PDF handling, and the manipulation of XML, strings, numbers, and dates, making it a comprehensive tool for developers. Furthermore, Lucee streamlines the process of both utilizing existing web services and crafting new ones, enhancing flexibility for users. As a project fueled by community contributions, we encourage participation in diverse ways. For those with coding skills, our Contributors guide serves as an excellent starting point. You can also join the conversation on our forum or contribute to the Lucee Association Switzerland's source code repository. Additionally, getting involved may include writing insightful articles for our newsletter or blog, helping to improve documentation, or providing valuable support in our forums. By contributing your time and skills, you can significantly strengthen the Lucee ecosystem, ensuring it remains a powerful and accessible resource for all users. Together, we can foster a collaborative environment that benefits everyone involved.

Apache TomEE, commonly known as "Tommy," is an application server that boasts full certification for Jakarta EE 9.1 and is built on the foundation of Apache Tomcat, starting from a standard Apache Tomcat zip file. The creation of TomEE begins with Apache Tomcat, and through the integration of essential libraries, it evolves into a packaged version that encompasses EE capabilities, resulting in the TomEE server. This server is recognized for its stability and readiness for production environments, as Apache TomEE 8.0 implements Java EE 8/Jakarta EE 8 while still supporting the javax namespace and functioning on Java 8 or later versions. It aligns primarily with the Jakarta EE 9.1 web profile and adopts the new jakarta namespace, ensuring compatibility with Java 11 or newer. There are four distinct variations of Apache TomEE available: web profile, MicroProfile, Plus, and Plume. The web profile variant of Apache TomEE delivers fundamental services such as servlets, JSP, JSF, JTA, JPA, CDI, bean validation, and EJB Lite, forming the core of the server's functionality. Meanwhile, the MicroProfile edition enriches the server with extended support for MicroProfile features, while the Plus and Plume versions further broaden capabilities by incorporating JMS, JAX-WS, and additional functionalities. In summary, Apache TomEE serves as a flexible and powerful option for developers who aim to utilize Jakarta EE in their software projects, making it an ideal choice for modern application development.

Apache Geronimo is a suite of open-source initiatives designed to provide JavaEE/JakartaEE libraries complemented by Microprofile implementations. Our primary goal is to offer reusable components that are not only extensively used but also well-maintained, ensuring developers have access to reliable tools. This framework delivers powerful libraries that comply with the specifications set forth by Java EE and Jakarta EE, while also placing a strong emphasis on OSGi bundle metadata for enhanced modularity. The XBean project aims to create a server with a plugin-based architecture akin to that of Eclipse's IDE, which will facilitate the discovery, download, and installation of server plugins from a centralized online repository. Additionally, the framework is versatile, supporting various IoC systems, and can operate seamlessly without one, while also providing JMX capabilities without the need for JMX-specific code. It effectively manages lifecycles and class loaders, and offers smooth integration with Spring to enhance functionality. Moreover, Apache Geronimo includes several Microprofile implementations and works on the Apache Geronimo Arthur project, which aspires to create a lightweight framework over Oracle GraalVM to augment its functionalities. Ultimately, Apache Geronimo is dedicated to continuously evolving to meet the diverse requirements of developers within the Java ecosystem, ensuring that the framework remains relevant and useful in a rapidly changing technological landscape.

Application servers that are suitable for production or containerized environments and support Jakarta EE and MicroProfile include a variety of options tailored for modern software development and deployment needs. These servers facilitate robust application development while ensuring compatibility with the latest enterprise standards.

Caddy simplifies your infrastructure by taking care of TLS certificate renewals, OCSP stapling, serving static files, reverse proxying, and managing Kubernetes ingress, among other functionalities. Its modular architecture enhances capabilities within a single, compact binary that can be compiled for any operating system. With no dependencies, including libc, Caddy excels in containerized environments, allowing for deployment in virtually any setting. It seamlessly acquires and renews TLS certificates for your websites, incorporating OCSP response stapling as a standard feature. The advanced certificate management features offered by Caddy are some of the most reliable and sophisticated in the industry. Built using Go, Caddy boasts superior memory safety over servers constructed with C. A robust TLS stack, supported by the Go standard library, constitutes the backbone of a significant portion of global Internet traffic. Functioning as both a flexible, efficient static file server and a powerful, scalable reverse proxy, Caddy proves to be a versatile solution for myriad applications. Furthermore, its intuitive configuration and smooth integration processes make it an attractive choice for developers who prioritize both simplicity and effectiveness in their projects. Caddy's capabilities not only enhance performance but also contribute to a more secure online environment.

Apache Tomcat® is a free and open-source software that implements the Jakarta Servlet, Jakarta Server Pages, Jakarta Expression Language, Jakarta WebSocket, Jakarta Annotations, and Jakarta Authentication specifications, which are all part of the Jakarta EE framework. This adaptable software plays a crucial role in a wide range of large-scale web applications that various sectors and organizations rely on. Users can share their experiences and insights on the PoweredBy wiki page dedicated to Tomcat. The Apache Tomcat Project is thrilled to unveil version 10.0.10 of Apache Tomcat, which includes updates from the Jakarta EE 9 platform. This latest iteration is designed to boost performance while delivering enhanced features that benefit developers and organizations across the board, ensuring they stay competitive in an evolving digital landscape. With each new release, the community looks forward to further innovations and improvements that will continue to facilitate the development of robust web applications.