npx

npx is a command that you type into a text window on the computer instead of clicking on icons. This text window is called a terminal or command line. With npx, you start a ready-made small program that other people have written and put on the internet. The special thing about it: you don’t have to permanently install this program on your computer beforehand. npx downloads it when needed, runs it, and then cleans up afterward. The command belongs to Node.js, a widely used environment in which programs written in the JavaScript language run.

The difference from permanent installation

In the past, every helper program first had to be installed permanently on the computer. After that, it just sat there, even if you only needed it once. After a few months, many developers had dozens of such tools installed without even remembering what they were for. npx makes this step unnecessary.

An even more important issue is a second problem: outdated versions. A permanently installed tool stays at the state it had when it was installed. Anyone starting a new project a year later unknowingly uses an old version. npx, by contrast, fetches the current version by default. That’s why almost every tutorial for a new web project today includes an npx command instead of an installation instruction.

A side effect concerns teamwork. When everyone runs the same npx command, everyone works with the same tool. With permanently installed programs, on the other hand, everyone has a slightly different version, which leads to hard-to-explain errors.

What happens when you type the command

npx first checks whether the desired program is already located in the current project folder. If it is there, exactly that version is started. If npx finds nothing, it searches the npm registry. This is a huge public repository with over two million JavaScript packages, comparable to an app store for programmers.

The matching package is then loaded into a temporary storage area called the cache. From there, npx starts the program immediately. The cache is kept for a while, so a second call of the same command is noticeably faster. You can think of it like a lending library: you take the book, use it, and don’t have to buy it.

However, this also creates a risk you should be aware of. You run foreign program code without inspecting it beforehand. A package with malicious content can thus reach your computer. Experts call this a supply chain attack. That’s why the rule applies: only use npx with packages whose names you have obtained from a trustworthy source.

npx in tutorials and in the AI world

npx is most commonly encountered in tutorials for websites. A command like “npx create-react-app my-page” sets up a complete project scaffold in a minute, with all folders and basic settings. Without this command, you would have to create dozens of files by hand. Similar startup commands exist for almost every modern web tool.

npx is also appearing more and more often in the AI field. Many add-on programs for chatbots and coding assistants are published as npm packages. Anyone who wants to connect an AI assistant to their calendar or database, for example, often starts the required connection service with a single npx call. In the configuration files of such tools, the command is then permanently stored.

A common misconception is that npx is a separate program that has to be downloaded specially. That’s not true. Since 2017, npx has come automatically bundled with npm, the package manager of Node.js. Anyone who installs Node.js already has npx. Still, the two should not be confused: npm installs and manages packages, npx runs them.