When a program is written in a certain language, then "in" is used. But I don't know what preposition to use with frameworks and libraries.

For example, I saw that some people say:

It's written in Node.js

But Node.js isn't a language, it's a runtime environment, so I would say:

It's written in JavaScript with/for Node.js

But if one doesn't want to mention a language explicitly, what preposition should be used?

Examples with frameworks:

  • A test written in/with Cypress
  • An app written in/with Express

Also, I wonder can "written" be omitted? For example:

There are many tests in/with Cypress

  • 2
    As a programmer, I see/hear both, but I tend to use with or using when referring to APIs or frameworks, e.g.,"That program is written with .NET". If, for some reason, I want to avoid using forms of the verb write, I'll generally use a form of use: "Those tests are using node.js". Mar 20, 2023 at 14:02

1 Answer 1


When referring to frameworks, libraries, or runtime environments, the preposition "with" is more appropriate than "in". For example;

A web app written with asp.net core

In this case, "with" is correct because ASP.NET Core is a framework, and the web app is developed with that framework. "with" is used to indicate that the mentioned framework or library is being utilized.

On the other hand, when referring to programming languages, "in" is more appropriate, because the app is written using that language. For example;

A web app written in c#

In this case, "in" is more appropriate than "with", because C# is a programming language, and the web app is written using that language. To combine the two, you can say;

A web app written with asp.net core in c#

You don't exactly use a framework or library itself. You utilize a framework or library. You make use of it. On the other hand, you directly use a programming language itself.

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