[opensourcedex]

spring-cloud-gateway is a free, open source api development & testing project written in Java and released under Apache-2.0. It has 4,908 GitHub stars, 3,478 forks and 548 open issues, and was last pushed 4 hours ago. On this registry it ranks #48 of 103 tracked projects in API Development & Testing, with 5 head-to-head comparisons available. It gained 2 stars over the last 3 tracked days.

What is spring-cloud-gateway?

What it is

spring-cloud-gateway is an API Gateway built on Spring Framework and Spring Boot, and it lives in the Java, Spring Cloud, and microservices ecosystem. It sits in front of services and decides how incoming HTTP requests should be proxied to downstream endpoints.

The concrete problem it solves is centralizing routing and request handling for Java microservices without writing separate proxy code for each service. It provides dynamic routing, route matching, and filters that can change downstream requests and responses before traffic reaches the application.

Key capabilities

  • It runs on Java 17, Spring Framework 6, and Spring Boot 3, fitting Spring Boot applications that use the Spring programming model.
  • It performs dynamic routing and builds route matching into Spring Handler Mapping, so routes can be resolved as part of the normal Spring request-handling flow.
  • It matches HTTP requests using request attributes such as path, method, header, and host, allowing different services to be reached from one gateway.
  • It applies filters scoped to matching routes, and those filters can modify the downstream HTTP request and HTTP response.
  • It supports filter actions named in the README, including adding or removing headers, adding or removing parameters, rewriting paths, setting paths, and circuit breaker behavior.
  • It can be driven by an API or by configuration, and it supports Spring Cloud DiscoveryClient for configuring routes from service discovery.

Who uses it and how

  • Java microservice teams use it as the front door for HTTP traffic, routing client requests to backend services that are registered with Spring Cloud or configured directly.
  • Operators use it when they need a proxy that can rewrite request paths, adjust headers and parameters, and apply circuit breaker behavior at the routing layer.
  • Developers use it in Spring Cloud projects where routes are defined through configuration or an API and resolved with Spring Handler Mapping and DiscoveryClient.
  • Contributors use it by building the source with JDK 17 and Maven, and by running tests that depend on middleware such as Redis inside Docker.

Getting started

The README describes building from source rather than a packaged install or deploy command: clone the project, use JDK 17 and Maven 3.3.3 or newer, and run ./mvnw install; Docker is needed for tests that require middleware such as Redis.

When to use it — and when not to

Use it when your platform already runs Java, Spring Framework 6, Spring Boot 3, and Spring Cloud, and you need gateway routing plus request/response filters close to the application stack. Avoid it if you want a language-neutral or fully hosted gateway, because the provided facts describe a Java/Spring project built from source and do not list a package manager, Docker image, hosted option, or external database/storage/SMTP dependency. Its 548 open issues and generated README point to active maintenance work and source editing through asciidoc rather than a ready-to-operate product.

project readme (upstream, from github) — read inline

//// DO NOT EDIT THIS FILE. IT WAS GENERATED. Manual changes to this file will be lost when it is generated again. Edit the files in the src/main/asciidoc/ directory instead. ////

image::https://github.com/spring-cloud/spring-cloud-gateway/workflows/Build/badge.svg?style=svg["Actions Status", link="https://github.com/spring-cloud/spring-cloud-gateway/actions"] image::https://codecov.io/gh/spring-cloud/spring-cloud-gateway/branch/main/graph/badge.svg["Codecov", link="https://codecov.io/gh/spring-cloud/spring-cloud-gateway/branch/main"]

[[features]] = Features

  • Java 17
  • Spring Framework 6
  • Spring Boot 3
  • Dynamic routing
  • Route matching built into Spring Handler Mapping
  • Route matching on HTTP Request (Path, Method, Header, Host, etc...)
  • Filters scoped to Matching Route
  • Filters can modify downstream HTTP Request and HTTP Response (Add/Remove Headers, Add/Remove Parameters, Rewrite Path, Set Path, Circuit Breaker, etc...)
  • API or configuration driven
  • Supports Spring Cloud DiscoveryClient for configuring Routes

[[building]] = Building

:jdkversion: 17

[[basic-compile-and-test]] == Basic Compile and Test

To build the source you will need to install JDK {jdkversion}.

Spring Cloud uses Maven for most build-related activities, and you should be able to get off the ground quite quickly by cloning the project you are interested in and typing

$ ./mvnw install

NOTE: You can also install Maven (>=3.3.3) yourself and run the mvn command in place of ./mvnw in the examples below. If you do that you also might need to add -P spring if your local Maven settings do not contain repository declarations for spring pre-release artifacts.

NOTE: Be aware that you might need to increase the amount of memory available to Maven by setting a MAVEN_OPTS environment variable with a value like -Xmx512m -XX:MaxPermSize=128m. We try to cover this in the .mvn configuration, so if you find you have to do it to make a build succeed, please raise a ticket to get the settings added to source control.

The projects that require middleware (i.e. Redis) for testing generally require that a local instance of https://www.docker.com/get-started[Docker] is installed and running.

[[documentation]] == Documentation

The spring-cloud-build module has a "docs" profile, and if you switch that on it will try to build asciidoc sources using https://docs.antora.org/antora/latest/[Antora] from modules/ROOT/.

As part of that process it will look for a docs/src/main/asciidoc/README.adoc and process it by loading all the includes, but not parsing or rendering it, just copying it to ${main.basedir} (defaults to $\{basedir}, i.e. the root of the project). If there are any changes in the README it will then show up after a Maven build as a modified file in the correct place. Just commit it and push the change.

You can generate the docs site using the following command:

[indent=0]

./mvnw -pl docs -P docs antora:antora

[[working-with-the-code]] == Working with the code If you don't have an IDE preference we would recommend that you use https://spring.io/tools[Spring Tools Suite] or https://eclipse.org[Eclipse] when working with the code. We use the https://eclipse.org/m2e/[m2eclipse] eclipse plugin for maven support. Other IDEs and tools should also work without issue as long as they use Maven 3.3.3 or better.

[[activate-the-spring-maven-profile]] === Activate the Spring Maven profile Spring Cloud projects require the 'spring' Maven profile to be activated to resolve the spring milestone and snapshot repositories. Use your preferred IDE to set this profile to be active, or you may experience build errors.

[[importing-into-eclipse-with-m2eclipse]] === Importing into eclipse with m2eclipse We recommend the https://eclipse.org/m2e/[m2eclipse] eclipse plugin when working with eclipse. If you don't already have m2eclipse installed it is available from the "eclipse marketplace".

NOTE: Older versions of m2e do not support Maven 3.3, so once the projects are imported into Eclipse you will also need to tell m2eclipse to use the right profile for the projects. If you see many different errors related to the POMs in the projects, check that you have an up to date installation. If you can't upgrade m2e, add the "spring" profile to your settings.xml. Alternatively you can copy the repository settings from the "spring" profile of the parent pom into your settings.xml.

[[importing-into-eclipse-without-m2eclipse]] === Importing into eclipse without m2eclipse If you prefer not to use m2eclipse you can generate eclipse project metadata using the following command:

[indent=0]

$ ./mvnw eclipse:eclipse

The generated eclipse projects can be imported by selecting import existing projects from the file menu.

[[contributing]] = Contributing

:spring-cloud-build-branch: main

Spring Cloud is released under the non-restrictive Apache 2.0 license, and follows a very standard Github development process, using Github tracker for issues and merging pull requests into main. If you want to contribute even something trivial please do not hesitate, but follow the guidelines below.

[[developer-certificate-of-origin]] == Developer Certificate of Origin (DCO)

All commits must include a Signed-off-by trailer at the end of each commit message to indicate that the contributor agrees to the Developer Certificate of Origin. For additional details, please refer to the blog post https://spring.io/blog/2025/01/06/hello-dco-goodbye-cla-simplifying-contributions-to-spring[Hello DCO, Goodbye CLA: Simplifying Contributions to Spring].

[[code-of-conduct]] == Code of Conduct This project adheres to the Contributor Covenant https://github.com/spring-cloud/spring-cloud-build/blob/main/docs/modules/ROOT/partials/code-of-conduct.adoc[code of conduct]. By participating, you are expected to uphold this code. Please report unacceptable behavior to [email protected].

[[code-conventions-and-housekeeping]] == Code Conventions and Housekeeping None of these is essential for a pull request, but they will all help. They can also be added after the original pull request but before a merge.

  • Use the Spring Framework code format conventions. If you use Eclipse you can import formatter settings using the eclipse-code-formatter.xml file from the https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/main/spring-cloud-dependencies-parent/eclipse-code-formatter.xml[Spring Cloud Build] project. If using IntelliJ, you can use the https://plugins.jetbrains.com/plugin/6546[Eclipse Code Formatter Plugin] to import the same file.
  • Make sure all new .java files to have a simple Javadoc class comment with at least an @author tag identifying you, and preferably at least a paragraph on what the class is for.
  • Add the ASF license header comment to all new .java files (copy from existing files in the project)
  • Add yourself as an @author to the .java files that you modify substantially (more than cosmetic changes).
  • Add some Javadocs and, if you change the namespace, some XSD doc elements.
  • A few unit tests would help a lot as well -- someone has to do it.
  • If no-one else is using your branch, please rebase it against the current main (or other target branch in the main project).
  • When writing a commit message please follow https://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html[these conventions], if you are fixing an existing issue please add Fixes gh-XXXX at the end of the commit message (where XXXX is the issue number).

[[checkstyle]] == Checkstyle

Spring Cloud Build comes with a set of checkstyle rules. You can find them in the spring-cloud-build-tools module. The most notable files under the module are:

.spring-cloud-build-tools/

└── src    ├── checkstyle    │   └── checkstyle-suppressions.xml    └── main    └── resources    ├── checkstyle-header.txt    └── checkstyle.xml

Default Checkstyle rules File header setup Default suppression rules

[[checkstyle-configuration]] === Checkstyle configuration

Checkstyle rules are disabled by default. To add checkstyle to your project just define the following properties and plugins.

.pom.xml

true true

    true






            io.spring.javaformat
            spring-javaformat-maven-plugin


            org.apache.maven.plugins
            maven-checkstyle-plu

readme truncated — read the full docs on github

Frequently asked questions

Is spring-cloud-gateway free to use?

spring-cloud-gateway is open source under the Apache-2.0 licence. There is no licence fee and no seat count — you can self-host it or, where the project offers one, pay a vendor for a managed version instead.

What does spring-cloud-gateway do?

An API Gateway built on Spring Framework and Spring Boot providing routing and more.

What is spring-cloud-gateway written in?

spring-cloud-gateway is primarily written in Java. Its source is publicly available at https://github.com/spring-cloud/spring-cloud-gateway, and it has 4,908 GitHub stars.