FlipJump IDE — fj.tomhe.app

🚀 Open the FlipJump IDE

What it is

A browser-based FlipJump development environment — nothing to install, just open the link. The editor runs in your browser; the assembler and interpreter run on the server (the real fj toolchain), and your program’s output streams back live over a WebSocket as it runs.

The editor is Monaco (the same engine VS Code uses). The tokenizer that powers its syntax highlighting is the source of truth for this site’s Pygments lexer too, so code blocks look identical across both.

What you can do

  • Write and run FlipJump straight from the browser — fj assembles and runs your code on the server and streams stdout/stderr into the terminal in real time.

  • Feed it input — the terminal is interactive, so programs that read stdin work too.

  • Compile to .fjm and download the assembled binary, or re-run an already-compiled image without recompiling.

  • Load pre-baked sample programs — Hello World, a calculator, the prime sieve, a function-call demo, and more.

  • Import from other languages — convert Brainfuck with bf2fj or C with c2fj and run the result.

  • Browse the language reference and STL in a side panel while you work.

  • Work across multiple files in a file tree; your open project persists in the browser between visits.

When to use it vs the local fj toolchain

Use case

Use this

First touch — try without installing anything

IDE

Building a small demo

IDE

Reading STL macro source while experimenting

IDE (side-by-side panels)

Long-running simulations

Local fj (the hosted runner has time limits)

Custom toolchain integration (Makefiles, CI)

Local fj

Keeping large projects under version control

Local fj

Source

The IDE is open source. The repo lives alongside this docs site under tomhea — see fj.tomhe.app.