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