Project / Rust · Tauri · Code editors · Developer tools

JCode

A cross-platform code editor and runner built around quick, unsaved scratchpads.

CodeRunner is one of my favourite macOS apps: open a buffer, write a few lines, and press Run. JCode is my take on that idea, with a bit more Jason-ness and a plan to bring the same scratchpad workflow to macOS, Windows, and Linux.

JCode running an unsaved Python scratchpad, with syntax highlighting and its output visible beside the editor. — 01
An unsaved Python scratchpad. JCode handles the temporary file and puts the result next to the code that produced it.

Why I made it

Most code editors assume I am about to start or open a project. Often I am not. I just want to test a regular expression, inspect a small response, try an unfamiliar API, or find out whether an idea works.

For that kind of job I like having a blank editor that is ready immediately. There is no file to name, project to create, or terminal to arrange. Pick a language, write the smallest useful thing, and run it.

JCode keeps that simple loop, then adds the things I missed when the experiment grew a little: better output, toolchain discovery, optional language-server help, and a debugger.

JCode paused at a breakpoint in a C program, with the current line and local variables visible. — 02
The debugger paused in a C program. Breakpoints, stepping, variables, the call stack, and expression evaluation stay in the same window.

What is in there

Scratchpads first. Unsaved tabs run like ordinary files and survive a relaunch, so saving can wait until an experiment becomes worth keeping.
Twenty-eight language modes. Twenty-six can run or render; CSS and Trio provide editing and highlighting without pretending there is something to execute. What is available on a particular machine depends on its installed toolchains.
Useful output. Build output, standard output, and errors remain distinct. Runs show their exit status, duration, and peak memory, and interactive programs can read from stdin.
Toolchains without guesswork. JCode finds installed compilers and interpreters, reports their versions, and makes missing dependencies visible.
Editor essentials. CodeMirror 6 provides highlighting, folding, search, multiple selections, and the usual editing conveniences. LSP support can add diagnostics, completion, and hover information.
Previews where they help. HTML renders beside the editor, Markdown becomes a preview, and LaTeX can compile to PDF.

JCode's language menu showing the available code runners and their keyboard shortcuts. — 03
The language menu in the current development build. JCode remembers the last choice and can start a scratchpad from a small language template.

Cross-platform direction

The current screenshots are from macOS, where development started, but JCode is not intended to be a macOS-only application. The interface is built with Svelte 5 and CodeMirror 6, with Rust and Tauri 2 underneath, and the plan is to support macOS, Windows, and Linux.

Some runners will naturally remain platform-specific—AppleScript is not going to become a Windows language—but the scratchpad, editor, output, and debugging experience should feel like the same application everywhere.

JCode preferences showing themes, editor font, spacing, wrapping, and indentation controls. — 04
Themes, fonts, line spacing, wrapping, indentation, ligatures, and a few other preferences for making the editor comfortable.

A few practical notes

JCode is a personal project and still in development. It does not try to replace a full IDE, manage a project tree, or provide an embedded terminal. The point is to make the space between a question and a small piece of running code pleasantly short.

Scratchpads are restored when the app reopens, and each language can have its own run command, environment, indentation, language server, and debug adapter.

Want to try it?

It is not yet available for public consumption, but watch this space.