# Server Extensions in Notebook 7

Notebook 7 is now based on Jupyter Server, which is a new server application that allows to run multiple Jupyter applications (e.g. Notebook, JupyterLab, NBClassic, etc.) on the same server.

This means that Notebook 7 is able to reuse many of the existing server extensions from the Jupyter ecosystem as is.

## Migration from the Notebook Server

The Jupyter Server documentation provides a [guide for migrating from the classic notebook server to Jupyter Server](https://jupyter-server.readthedocs.io/en/latest/operators/migrate-from-nbserver.html)

## Authoring Server Extensions

The Jupyter Server documentation provides a [guide for authoring server extensions](https://jupyter-server.readthedocs.io/en/latest/developers/extensions.html)