Introduction

Helidon SE is Helidon’s foundational set of APIs and, as of Helidon 4, it uses virtual threads to enable these APIs to change from asynchronous to blocking.

Components

The REST framework for Helidon SE is the Helidon WebServer. It was built from the ground up to take full advantage of Java 21’s virtual threads.

Helidon SE supports a number of additional Helidon features:

Config

A flexible configuration framework with support for multiple sources and formats.

CORS

Add support for CORS to your application using a Helidon module.

DB Client

Provides a unified, reactive API for working with databases in non-blocking way.

GraphQL

Build GraphQL servers.

gRPC

Build gRPC servers and clients.

Health Checks

Expose health statuses of your applications.

Injection

Use of the Helidon injection in your applications.

JSON Schema

Creation of the JSON Schema in your applications.

Metrics

Instrumentation to expose metrics of your applications.

OpenAPI

Support OpenAPI from your application.

Reactive Messaging

Use prepared tools for repetitive use case scenarios.

Reactive Streams

APIs to work with reactive streams in Helidon.

Security

A tool-chain to handle authentication, authorization and context propagation.

Tracing

Profile and monitor your applications across multiple services.

WebClient

HTTP client that handles responses to the HTTP requests.

WebServer

A programmatic HTTP API that uses virtual threads to handle nearly unlimited concurrent requests without blocking a platform thread or starving other requests.

WebSocket

Enables Java applications to participate in WebSocket interactions as both servers and clients.

Upgrade

In case you need to upgrade the version of Helidon, follow the upgrade guides:

Helidon SE 4x Upgrade Guide

Follow this guide to migrate your application from Helidon 3.x to 4.x.

Helidon SE 3x Upgrade Guide

Follow this guide to migrate your application from Helidon 2.x to 3.x.

Helidon SE 2.x Upgrade Guide

Follow this guide to migrate your application from Helidon 1.x to 2.x.

Next Steps

Try the Helidon SE quickstart guides to get your first Helidon SE application up and running in minutes.

Guides

Follow step-by-step guides to build your applications using Helidon SE.

Javadocs

Browse the Helidon Javadocs.