> ## Documentation Index
> Fetch the complete documentation index at: https://mbcz.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Installation

> Install OmniSync on backend and proxy servers

## Requirements

* **Java 21+**
* **Paper or Folia backend servers**
* **Velocity proxy** for transfer protection
* **Redis 6+**
* **OmniSync license key**

<Note>
  Purpur is Paper-based and may work on compatible builds, but test it on your exact
  target version before advertising or using it in production.
</Note>

## Files

Use the release jars:

```text theme={null}
OmniSync-Paper-1.0.0-o.jar
OmniSync-Velocity-1.0.0-o.jar
```

## Backend Setup

1. Stop each backend server.
2. Place `OmniSync-Paper-1.0.0-o.jar` into each backend `plugins` folder.
3. Start each backend once to generate `plugins/OmniSync/config.yml`.
4. Stop each backend again.
5. Set your `license-key`.
6. Set the same `redis-uri` and `redis-key-prefix` on every backend in the same network.
7. Set a unique `server-name` on every backend.
8. Start the backend servers.

## Velocity Setup

1. Stop the Velocity proxy.
2. Place `OmniSync-Velocity-1.0.0-o.jar` into the proxy `plugins` folder.
3. Start Velocity once to generate `plugins/omnisync/config.properties`.
4. Stop Velocity again.
5. Set your `license-key`.
6. Set the same `redis-uri` and `redis-key-prefix` used by the backend servers.
7. Start Velocity.

## License Key

Paper config:

```yaml theme={null}
license-key: "YOUR_KEY_HERE"
```

Velocity config:

```properties theme={null}
license-key=YOUR_KEY_HERE
```

The legacy key name `license_key` is also accepted.

<Warning>
  If the license key is missing, invalid, or the license API cannot be reached,
  OmniSync will not run.
</Warning>

## Redis Setup

All backend servers and the Velocity proxy must reach the same Redis instance.

```yaml theme={null}
redis-uri: "redis://localhost:6379"
redis-key-prefix: "omnisync"
```

Use a different `redis-key-prefix` for test, staging, and production networks.