What is a .jl file?
Julia Source File · Code and data · Julia project (MIT) · 2012
A .jl file is Julia source code, a language built for high-performance scientific and numerical computing. It aims to be as easy to write as Python but as fast as C, which makes it popular in research.
What is a .jl file used for?
Julia uses just-in-time compilation to reach speeds close to C while keeping a readable, high-level syntax. It is strong in data science, machine learning and numerical simulation, competing with Python, R and MATLAB.
The files are plain text; VS Code with the Julia extension, or a Pluto/Jupyter notebook, are common environments.
What opens a .jl file?
The .jl format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list.
Windows
- VS Code (Julia)
- Julia REPL
- any text editor
macOS
- VS Code (Julia)
- Julia REPL
- any text editor
Linux
- VS Code (Julia)
- Julia REPL
- any text editor
Open a .jl file step by step
- Confirm the file really is a .jl. Drop it into the WhatFileType identifier, which reads its signature in your browser without uploading anything.
- On Windows, open it with VS Code (Julia) or Julia REPL.
- On Mac, use VS Code (Julia) or Julia REPL.
- On Linux, try VS Code (Julia) or Julia REPL.
- Still stuck? Search for a dedicated Julia viewer rather than a generic one.
Why can't I open my .jl file?
Almost always because no installed app understands Julia. Install one of the apps above, or convert the file to a format your existing software already reads. If double-clicking opens the wrong program instead of nothing at all, the file association is set to the wrong app rather than the file being broken.
The other possibility is that the file is not really a .jl at all. Drop it into the file identifier to check it by its bytes instead of its name. Nothing is uploaded.
Julia has no fixed magic number, so there is no signature table on this page. Its bytes alone do not prove the format: identification relies on the extension, the structure of the content and the program that created it. The magic-numbers reference lists the formats that do carry one.
Frequently asked questions
What is a .jl file?
A .jl file is Julia source code, a language built for high-performance scientific and numerical computing. It aims to be as easy to write as Python but as fast as C, which makes it popular in research.
How do I run a .jl file?
With Julia installed, run julia file.jl from a terminal, or execute it in the Julia REPL or VS Code.
Is Julia faster than Python?
For heavy numerical work, usually yes: Julia's just-in-time compilation approaches C speed, while keeping a high-level syntax. Python often relies on C libraries to match it.
What is Julia used for?
Scientific and numerical computing: data science, machine learning, simulations and research where both speed and readable code matter.
Related formats
Sources
Details on this page were checked against authoritative references. How sources are ranked and what is deliberately left out is set out in the methodology.