# Introduction

Package JVM applications into self-contained binaries. No JVM installation required to run the output.

## What is jbundle?

**jbundle** transforms JVM applications (Clojure, Java, Kotlin, Scala, Groovy) into self-contained binaries. Think of it as the Go/Rust distribution experience for the JVM world.

```bash
# Build your app
jbundle build --input ./my-app --output ./dist/my-app

# Run anywhere (no Java required)
./dist/my-app
```

## Why jbundle?

The conventional deployment approach requires both a JAR and a JVM on the target machine. GraalVM native-image is an alternative, but presents challenges: slow compilations, complex reflection configuration, and library incompatibilities.

**jbundle offers a practical solution:** bundle a minimal JVM runtime with your uberjar into a single executable. The result is a single file, no external dependencies, with full JVM compatibility.

## Key Features

| Feature                | Description                                   |
| ---------------------- | --------------------------------------------- |
| **Single binary**      | One file to distribute, like Go or Rust       |
| **No JVM required**    | Runtime is bundled inside the binary          |
| **Fast startup**       | AppCDS + profiles achieve \~200-350ms startup |
| **Full compatibility** | Everything that works on JVM works here       |
| **Multiple languages** | Clojure, Java, Kotlin, Scala, Groovy          |
| **Smart caching**      | Layers cached independently by content hash   |

## How It Works

```
detect → build uberjar → download JDK → jdeps → jlink → pack
```

1. **Detect** — Identifies your build system (deps.edn, project.clj, pom.xml, build.gradle)
2. **Build** — Runs the appropriate build command to create an uberjar
3. **Download JDK** — Fetches JDK from Adoptium (cached locally)
4. **Analyze** — Uses jdeps to detect required modules
5. **Minimize** — Creates minimal runtime with jlink (\~30-50 MB)
6. **Package** — Bundles everything into a single executable

## Quick Comparison

| Aspect            | jbundle              | GraalVM native-image            |
| ----------------- | -------------------- | ------------------------------- |
| **Compatibility** | 100% JVM compatible  | Requires reflection config      |
| **Build time**    | Fast                 | Slow (AOT compilation)          |
| **Startup**       | \~200-350ms (AppCDS) | \~10-50ms                       |
| **Setup**         | Just `jbundle`       | GraalVM + native-image + config |

## Next Steps

* [Installation](/getting-started/installation.md) — Get jbundle on your system
* [Quick Start](/getting-started/quick-start.md) — Build your first binary
* [Configuration](/user-guide/configuration.md) — Customize with `jbundle.toml`


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://jbundle.avelino.run/readme.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.