---
title: "Prerequisites"
url: https://docs.catalyst.zoho.com/en/tutorials/alien-city-appsail/express/prerequisites/
description: "Create an application and host it on Catalyst using the Catalyst AppSail service and Catalyst Data Store that allows you to report or look up alien encounters in a city."
last_updated: 2025-09-29T11:02:42Z
service: All Services
type: tutorial
related_links:
  - name: "Catalyst CLI Documentation"
    url: /en/cli/v1/cli-command-reference/
---

# Prerequisites

Before you begin building the application, you must have the following prerequisites installed on your system:

1. [Catalyst CLI](https://docs.catalyst.zoho.com/en/cli/v1/cli-command-reference/)
Catalyst CLI contains a host of tools that allow you to initialize, develop, test, and deploy the components of your application from your local machine. We will be working with Catalyst CLI in this tutorial.
 You must perform the following actions:

    * **Install Catalyst CLI**: Catalyst CLI is installed through NPM. You must therefore have NPM and Node.js installed on your system before you install the CLI. Refer to the [Install Catalyst CLI help page](https://docs.catalyst.zoho.com/en/getting-started/installing-catalyst-cli/) for details on the pre-requisites and the steps to install it.
    * **Log in to Catalyst CLI**: After you install Catalyst CLI, you must authenticate the CLI with your Catalyst account before using it. Refer to the [CLI Login help page](https://docs.catalyst.zoho.com/en/cli/v1/login/login-from-cli/) for the steps to log in from Catalyst CLI and the various options available for it.

2. **Any IDE tool for application development for HTML and JavaScript**
You can use any IDE to code your application. Some popular choices include Visual Studio Code, IntelliJ IDEA, Eclipse, and Sublime Text. Download and install an IDE of your choice on your system.

> If you are a Visual Studio Code IDE user, you can install the **Catalyst Tools** extension, and use your IDE itself in place of the CLI. You can find more details about the Catalyst VS Code extension from this [help section](https://docs.catalyst.zoho.com/en/catalyst-extensions/vs-code-extension/introduction/).