best Java API Gateway libraries in 2025

Java API gateway is software that accepts an app's user request, diverts it to other backend services, gathers the necessary info, and supplies it to the application user in a single, combined package. It also provides analytics, threat protection layers, and other application security. Java API gateway is a common entry point for all API calls that come into an app, whether hosted on-premises or in the cloud. It receives remote requests and returns the requested data. Consider the web application of a restaurant. Even though all that information is gathered and delivered from various backend microservices or APIs, a user can enter a single request and easily access the: 

• Restaurant's menu,
• Diners' photos
• Reviews
• Payment service, and
• A map to check its location using a laptop or cellphone. 

An API gateway receives and processes their request. Developers use microservices in DevOps organizations to build and deploy apps in a fast-paced, iterative manner. API gateways provide three key services between a user and a collection of microservices: request routing, API composition, and protocol translation. In addition to simply servicing requests, an API gateway adds value by making data available in a format appropriate for the requestor's technology. For example, someone using a web browser to request information about a retail store receives far more information than someone using a mobile phone to request and view the same store's data. 

APIs are one of the most standard ways for microservices to communicate with one another. As integration and interconnectivity gain importance, APIs are becoming more and more crucial daily for software developers. Furthermore, APIs are used to provision infrastructure in modern cloud development, including the serverless model, and can use Java API gateway to deploy and manage serverless functions. 

Several Java API libraries help engineers to reuse code for networking other functionalities of the applications. Some examples of standard libraries are- scalecube-services, service-proxy, kong-java-client, aws-gateway-executor, gateleen, handyman, API-gateway, product-microgateway, shenyu, ship-gate, among others. 

Check out the below list to find the best top 10 Java API gateway libraries for your application development: