Creating Your First Micronaut Application

Introduction

Micronaut is a modern, cloud-native Java framework built for microservices and serverless applications. Unlike traditional Java frameworks, Micronaut focuses on:

Fast startup times
Low memory consumption
Compile-time dependency injection

In this tutorial, you will create your first Micronaut application from scratch using the package name com.kscodes.micronaut. Don’t worry — no prior experience with Micronaut is required!

Creating Your First Micronaut Application

Why Micronaut?

Before we jump into coding, let’s understand why many developers choose Micronaut:

Minimal runtime overhead.
No reflection — faster and safer.
Built-in support for reactive programming.
Great for microservices architecture.
Excellent integration with cloud services.

Prerequisites

Before we begin, make sure you have the following:

Tool	Version	Install Link
Java	17 or higher (Java 21 recommended)	Adoptium
Micronaut CLI	Latest	Micronaut Installation Guide
Gradle	Bundled (no need to install separately)	N/A
IDE	IntelliJ IDEA / Eclipse / VS Code

For a maven based project you can go through the Installing Micronaut CLI and Setting Up Your First Project

Step 1 — Install Micronaut CLI

Install via SDKMAN

If you use SDKMAN, installation is super easy:

1 2	sdk install micronaut

Verify installation

mn --version

Step 2 — Generate Micronaut Application

Now let’s scaffold your first Micronaut application.

mn create-app com.kscodes.micronaut.demo –build=gradle –lang=java

com.kscodes.micronaut.demo — package name
--build=gradle — Gradle as the build system
--lang=java — language is Java

✅ Tip: You can replace demo with your project name.

Step 3 — Understanding Project Structure

Micronaut will generate a ready-to-use project:

demo/

├── build.gradle

├── src/

│ ├── main/

│ │ ├── java/com/kscodes/micronaut/demo/

│ │ │ └── Application.java

│ └── test/

├── gradlew

└── README.md

Step 4 — Writing Your First REST Endpoint

Let’s build a simple greeting API.

Create Controller

Create a new file:
src/main/java/com/kscodes/micronaut/demo/GreetingController.java

package com.kscodes.micronaut.demo;

import io.micronaut.http.annotation.Controller;

import io.micronaut.http.annotation.Get;

@Controller("/greet")

public class GreetingController {

@Get("/{name}")

public String greet(String name) {

return "Hello, " + name + "!";

}

Explanation

@Controller("/greet") — base URL path.
@Get("/{name}") — accepts name as a path parameter.
Returns a greeting message.

Step 5 — Run the Application

Start the application:

gradlew run

Step 6 — Test the API

Open your browser or API tool (Postman, Curl, etc.)

http://localhost:8080/greet/John

Response

Hello, John!

🎉 Congratulations! You’ve successfully created your first Micronaut REST API.

Step 7 — Add Health Check

Micronaut provides built-in health endpoints.

Enable Management Endpoints

Add to src/main/resources/application.yml:

micronaut:

application:

name: demo

server:

port: 8080

endpoints:

health:

enabled: true

sensitive: false

Now visit:

http://localhost:8080/health

You’ll see health information for your app.

Step 8 — Build a Fat JAR

To package the application for deployment:

gradlew assemble

The fat JAR will be in:

build/libs/

Step 9 — Where to Go Next

Now that you have your basic Micronaut app running, you can explore:

Micronaut Data — for database access.
Micronaut Security — for authentication/authorization.
Micronaut Messaging — for Kafka/RabbitMQ integration.
Deploy to Cloud — AWS Lambda, Google Cloud Functions, Azure Functions.

Conclusion

Micronaut simplifies microservices development while keeping things blazing fast and memory-efficient. You’ve successfully:

Installed Micronaut CLI
Created your first Micronaut app
Built and tested a REST API

From here, the Micronaut ecosystem offers a huge set of features to explore.