# Helidon

> Helidon is a cloud-native, open-source Java framework for writing microservices that run on a fast web core powered by Java virtual threads.

Select the documentation that matches your project's Helidon version.

## Site

- [Helidon Project](https://helidon.io/): Java libraries crafted for Microservices
- [Helidon Documentation](https://helidon.io/docs): Explore Helidon
- [Helidon Níma](https://helidon.io/nima): Java virtual threads based microservices
- [Helidon Starter](https://helidon.io/starter): Generate Your Helidon Project

## Get Started

- [Helidon CLI](https://helidon.io/docs/core/latest/raw/cli.md): Create and manage Helidon projects
- [Get Started](https://helidon.io/docs/core/latest/raw/get-started.md): Set up your environment and run a Helidon application

## Documentation

- [Helidon Core](https://helidon.io/docs/core/v27/llms.txt): llms.txt index. First JDK aligned release. Previously known as Helidon SE.
- [Helidon V4](https://helidon.io/docs/v4/llms.txt): llms.txt index. Virtual Thread based. Includes Helidon SE and Helidon MP.
- [Helidon V3](https://helidon.io/docs/v3): Non-blocking & reactive, implemented on top of Netty. Includes Helidon SE and Helidon MP.
- [Helidon V2](https://helidon.io/docs/v2): Netty based. Includes Helidon SE and Helidon MP. EOL since June 2025.
- [Helidon V1](https://helidon.io/docs/v1): Netty based. Includes Helidon SE and Helidon MP. EOL since February 2022.
- [Helidon MCP Extension](https://github.com/helidon-io/helidon-mcp/blob/main/docs/README.md): Build Model Context Protocol servers and tools in Java.
- [Helidon LangChain4j Extension](https://github.com/helidon-io/helidon-extensions/blob/main/extensions/langchain4j/docs/README.md): Add AI services, agents, and RAG to Helidon applications.
- [Helidon OCI SDK v3 Extension](https://github.com/helidon-io/helidon-extensions/blob/main/extensions/oci-v3/docs/README.md): Integrate Helidon applications with Oracle Cloud Infrastructure through OCI SDK v3.
- [Helidon Kafka Extension](https://github.com/helidon-io/helidon-extensions/blob/main/extensions/messaging/kafka/modules/kafka/README.md): Connect Helidon applications to Apache Kafka.
- [Helidon Pulsar Extension](https://github.com/helidon-io/helidon-extensions/blob/main/extensions/messaging/pulsar/modules/pulsar/README.md): Connect Helidon applications to Apache Pulsar.
- [Helidon Jakarta JMS Extension](https://github.com/helidon-io/helidon-extensions/blob/main/extensions/messaging/jms/modules/jms/README.md): Connect Helidon applications to Jakarta Messaging providers.
- [Helidon javax JMS Extension](https://github.com/helidon-io/helidon-extensions/blob/main/extensions/messaging/jms-javax/modules/jms-javax/README.md): Connect Helidon applications to legacy javax.jms messaging providers.
- [Helidon Eureka Extension](https://github.com/helidon-io/helidon-extensions/blob/main/extensions/eureka/docs/README.md): Register and discover Helidon services with Netflix Eureka.
- [Helidon HashiCorp Vault Extension](https://github.com/helidon-io/helidon-extensions/blob/main/extensions/hashicorp-vault/docs/README.md): Access HashiCorp Vault secrets and authentication from Helidon applications.
- [Helidon OpenAPI Generator Extension](https://github.com/helidon-io/helidon-extensions/blob/main/extensions/openapi-generator/docs/README.md): Generate Helidon SE declarative server code from OpenAPI 3 specifications.
- [Helidon OpenAPI UI Extension](https://github.com/helidon-io/helidon-extensions/blob/main/extensions/openapi-ui/docs/README.md): Serve an interactive OpenAPI browser UI from Helidon applications.
- [Helidon CRaC Extension](https://github.com/helidon-io/helidon-extensions/blob/main/extensions/crac/docs/README.md): Provide Helidon hooks for coordinated JVM checkpoint and restore.
- [Helidon TOML Extension](https://github.com/helidon-io/helidon-extensions/blob/main/extensions/toml/docs/README.md): Parse TOML and load application/toml sources through Helidon Config.
- [Helidon Gson Extension](https://github.com/helidon-io/helidon-extensions/blob/main/extensions/gson/docs/README.md): Add Gson-backed JSON media support to Helidon SE WebServer.
- [Helidon Neo4j Extension](https://github.com/helidon-io/helidon-extensions/blob/main/extensions/neo4j/docs/README.md): Configure Neo4j drivers and health checks for Helidon applications.

## Examples

The Helidon examples are located in https://github.com/helidon-io/helidon-examples, with a separate branch per codeline.

- [Helidon 27.x](https://github.com/helidon-io/helidon-examples/tree/helidon-27.x)
- [Helidon 4.x](https://github.com/helidon-io/helidon-examples/tree/helidon-4.x)
- [Helidon 3.x](https://github.com/helidon-io/helidon-examples/tree/helidon-3.x)
- [Helidon 2.x](https://github.com/helidon-io/helidon-examples/tree/helidon-2.x)
- [Helidon 1.x](https://github.com/helidon-io/helidon/tree/helidon-1.x/examples)

## Contact Us

- [Slack](https://slack.helidon.io)
- [GitHub issues](https://github.com/helidon-io/helidon/issues)
- [GitHub discussions](https://github.com/helidon-io/helidon/discussions)