---
title: index.[tj]s
sidebar_position: 1
---

# index.[tj]s

A file that extends the Modern.js Web Server. You can add [Hooks](/apis/app/runtime/web-server/hook) or [Middleware](/apis/app/runtime/web-server/middleware) to the Web Server started by the application project in this file.

You can intercept and process requests and responses, perform authentication and role verification, preprocess requests, and catch exceptions. You can also insert specific business logic into the built-in processing logic (including route matching, resource addressing, header injection, page rendering, and static web hosting).
