## Default ports

SignBox Optimizer exposes the following ports:

| Service | Port | Purpose |
|  --- | --- | --- |
| Optimizer | 16100 | API requests from client applications |
| Optimizer | 5678 | Internal communication |
| Redis | 6379 | In-memory data store |


Port **16100** is the main entry point for signing requests.

## Custom port configuration

To use a different host port, update the port mapping in the `docker-compose.yml` file. The `ports` section maps host ports to container ports in the format `host_port:container_port`.

Example: to expose the API on host port 16100, ensure the following line exists:


```yaml
ports:
  - "16100:16100"
  - "5678:5678"
```

![SignBox docker-compose port 16100 configuration](/assets/signbox-docker-compose-port-16100.0c7c962b4426dae56b49d91d96d656209fbf629fa212349f29923642a526e312.003f76b7.png)

Change the left value (e.g. `"18000:16100"`) to bind a different host port to the container's port 16100.