Getting Started

Welcome to Just 🎉

Just is a command line tool optimizing Spring Boot developer experience. At this stage it's main feature is just run.

just run is a single command you need to start Spring Boot application in the development mode. It takes care of:

live reload - just live reloads the application whenever the code changes without a need for rebuilding, recompiling or restarting application. Just hit save in Intellij IDEA and just will compile the modified code and change will be reflected in the running application within seconds.
zero-config infrastructure services - just starts infrastructure services like databases and message queues without any additional configuration. As soon as it detects that your application connects to a service it starts the docker container and configures the application to connect to it. The best part - services start only once and don't affect the live reload performance at all.
docker compose - if you use docker-compose.yml to define local development environment, just will run docker compose up before it starts the application. It also live reloads Docker containers when the docker-compose.yml file changes.

just run command chooses the best command to run the project - Maven or Gradle, Maven Daemon or Maven Wrapper - it is all done automatically.

Installing

just is distributed as a native binary available currently for following operating systems and architectures:

just itself is a native executable, but it attaches dependencies to projects that require Java 11+.
Docker must be installed and running for provisioning infrastructure services.
the application run with just needs to be compatible with Spring Boot Devtools - most likely it is, but I've seen some applications that are unable to run once the spring-boot-devtools dependency is added

just works with both Spring Boot 2.x and 3.x applications.