How to open a .elm file (Windows, Mac, Linux)

Q: Why can't I open my .elm file?

Usually your computer lacks an app that understands Elm. Install one of the apps listed here, or convert the file to a more common format.

A .elm file is a Elm Source File. If double-clicking does nothing, your computer simply does not have an app that reads Elm yet. Here is how to fix that on each operating system, using free software wherever possible.

Open a .elm file step by step

Confirm the file really is a .elm. Drop it into the WhatFileType file identifier, which reads its signature without uploading anything.
On Windows, open it with VS Code (Elm extension) or any text editor.
On Mac, use VS Code (Elm extension) or any text editor.
On Linux, try VS Code (Elm extension) or any text editor.
Still stuck? Convert the .elm to js (compiled), which opens more widely.

Best apps to open .elm files

Windows

VS Code (Elm extension)
any text editor

macOS

VS Code (Elm extension)
any text editor

Linux

VS Code (Elm extension)
any text editor

Before you open it: Caution. An .elm file is program source that compiles to JavaScript. The text is harmless; review code before building and shipping it.

Frequently asked questions

Why can't I open my .elm file?

Almost always because no installed app understands Elm. Install one of the apps above, or convert the file to a format your existing software already reads.

How do I run an .elm file?

Install Elm and run elm reactor for a quick dev server, or elm make src/Main.elm to compile it to JavaScript or HTML you open in a browser.

Does Elm really have no runtime exceptions?

In practice, yes. The compiler forces every case (no null or undefined), so the classic JavaScript crashes cannot occur in pure Elm code.