Introduction

Helidon is a Java framework for building cloud-native applications. It provides APIs and runtime services for creating standalone applications that are easy to develop, deploy, observe, and scale.

Helidon Core is the foundational framework previously called Helidon SE. This documentation calls it Helidon unless it must distinguish it from another Helidon project. Some CLI and archetype identifiers still use the se flavor name.

Helidon applications run as standalone JVM processes, are powered by the Helidon WebServer, and give you a direct programming model for defining routes, services, configuration, security, observability, and other application behavior.

Helidon 27 requires Java 27 and uses virtual threads throughout the WebServer, so applications can use a simple blocking style without tying up platform threads for each request.

You write straightforward Java code while Helidon handles high-concurrency request processing on virtual threads.

Strengths

Full control over application structure and behavior.
Transparent programming model with explicit APIs.
High-concurrency services that benefit from virtual threads.
Small runtime footprint.
Few third-party dependencies.
Lightweight HTTP services and microservices.

First Look

A Helidon application can start an HTTP server and define a route directly in Java:

WebServer.builder()
    .addRouting(HttpRouting.builder()
        .get("/greet", (req, res)
            -> res.send("Hello World!")))
    .build()
    .start();

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Get Started

Set up your environment and run a Helidon application

Overview

Helidon Modules