# Caplin Trader 5 requirements

This page describes the requirements for running a Caplin Trader 5 development environment.

## Requirements

Caplin Trader 5 has the following requirements:

* Node.js 18, including a build environment for native modules. See [Installing Node.js](installing-node-js.md).
* Yarn package manager (latest version). See [Installing Yarn](installing-yarn.md).

  **📌 NOTE**\
  There is a [known issue](https://github.com/npm/npm/issues/18638) in versions of `npm` later than 4 that prevents npm from working with Caplin Trader 5 projects.
* Caplin CLI. See [Installing Caplin CLI](installing-caplin-cli.md).
* Internet access to the following public software repositories:
  * The npm registry (https://registry.npmjs.org)
  * GitHub (https://github.com)
* If you access the Internet through a corporate proxy server that supports only NTLM authentication, then you need an intermediate proxy server to handle NTLM authentication on behalf of [npm](https://docs.npmjs.com/) and [Yarn](https://yarnpkg.com). See [Internet access and corporate proxy servers](#internet-access-and-corporate-proxy-servers), below.

## Internet access and corporate proxy servers

Neither [npm](https://docs.npmjs.com/) nor [Yarn](https://yarnpkg.com) provide built-in support for [NTLM](https://en.wikipedia.org/wiki/NT_LAN_Manager) authentication to web proxies.

If you access the Internet via a corporate proxy that requires NTLM authentication, then possible solutions include:

* Configure npm and Yarn to use an alternative proxy server, if one is available, that allows [basic HTTP authentication](https://developer.mozilla.org/en-US/docs/Web/HTTP/Guides/Authentication) for specific users and websites.
* Configure npm and Yarn to use a local proxy (local to your development machine) that appends NTLM authentication headers before forwarding traffic to the main corporate proxy.

Contact your company’s IT support desk for a solution suitable for your network.