pyde

A self-contained, single-file Python IDE that runs entirely in the browser — no server, no install, no build step. Double-click index.html, or use it live at milesberry.net/pyde.

Built for teaching (GCSE/A Level CS style exercises), but useful for any quick "write and run some Python" need.

Features

• Run Python — full CPython 3.12, compiled to WebAssembly (via Pyodide), executing directly in your tab. stdout/stderr are captured and shown in the console, with errors colour-coded.
• Syntax highlighting — CodeMirror 5 with a Python mode and the Dracula theme.
• Multi-cursor editing — select a word and press Cmd-D / Ctrl-D to select the next occurrence, VS Code / Sublime style.
• Block comment / indent — select some lines, press # to toggle a comment prefix on all of them, or Tab / Shift-Tab to indent/dedent the block.
• Download / Upload — save your code as a .py file, or load one from disk.
• Virtual input file — paste text into the "Program input file" box and it's readable from Python via open("filename"). Any files your program writes are picked up automatically and offered as downloads.
• Turtle graphics — import turtle (or from turtle import *) renders to an on-page canvas.
• p5.js sketches — write setup() / draw() functions and call p5.background(...), p5.ellipse(...), etc. p5.js is loaded from CDN on demand.
• Parsons puzzles — turn the current code into a drag-and-drop line-reordering puzzle, with a Check button that highlights right/wrong placements. Shareable as a standalone puzzle link.
• Share via URL — the whole program (or just a Parsons puzzle) is LZ-compressed into the page's URL hash, so a link fully reproduces it with no backend.
• Tidy — auto-formats the code to PEP8 style with autopep8, installed on demand via micropip the first time it's used.

Supported libraries

Because Python is run via Pyodide, most of the standard library works out of the box, including:

math, random, string, re, datetime, itertools, collections, json, statistics, decimal, fractions, functools, dataclasses, enum, typing, textwrap, copy, heapq, bisect, and more.

A couple of modules are shimmed rather than the real thing, because the browser sandbox can't support them as-is:

• turtle — the real stdlib turtle needs Tkinter, which isn't available in a WebAssembly browser build. Instead, import turtle / from turtle import * loads a custom canvas-backed replacement covering the common API: forward, backward, left, right, goto, circle, penup/pendown, color/pencolor/fillcolor, begin_fill/end_fill, write, Screen(), and the usual short-form aliases (fd, bk, lt, rt, ...).
• p5 — not a real PyPI package. Detected when your code contains import p5 / from p5 import or a def draw(): function, this loads p5.js from CDN and exposes it as a Python module. import p5; p5.whatever(...) forwards any p5.js call, camelCase and all. from p5 import * also works, for a curated set of the common drawing/canvas/colour functions — including the snake_case and Processing-style names (no_fill, no_stroke, size for canvas sizing, ...) that convention expects, alongside the plain camelCase ones. Anything that would shadow a Python builtin (map, min, max, print, pow, ...) is deliberately left out of that starred set — remap is provided in place of map, and the rest stay reachable via p5.min(...) etc. Live-valued properties like width, mouseX, or frameCount aren't star-importable either (there's no way to make a plain Python name "live"), so use p5.width and friends for those.

Not supported: anything needing real OS features — tkinter (GUI), socket (raw networking), subprocess, multiprocessing, real threads, or the real filesystem (there's an in-memory virtual filesystem instead, used for the input/output file feature). Third-party PyPI packages (numpy, pandas, etc.) aren't loaded — there's no pip/micropip wiring, so only what ships with Pyodide's base distribution is available.

input() works. For plain (non-turtle, non-p5) programs, it shows an inline text box right in the console, keeping the full scrollback visible while you answer — this covers both input() at top-level code (a guess-the-number loop) and input() called from inside a helper function (very common — e.g. a get_guess() function, or a whole game wrapped in its own def), including chains of functions calling each other. If a program uses turtle/p5, or does something with input() too dynamic to safely rewrite (aliasing a function, passing it around as a value, recursion, decorators, a name shadowed elsewhere in the file), it falls back to a native prompt() dialog instead. See colophon.md for how (and why it can't always avoid the popup).

time.process_time() doesn't work — it always reads 0.0, even across genuine CPU-bound work, because it relies on OS-level CPU accounting that doesn't exist inside a WebAssembly sandbox. Use time.time() or time.perf_counter() for timing code instead; both work correctly.

There's currently no way to stop a running program from the page — an infinite loop or a long time.sleep() will freeze the tab, since Python runs on the same thread as the page itself. Reload the tab to recover.

Running it locally

There's nothing to install. Open index.html directly in a browser, or serve the folder with any static file server if you prefer.

License

MIT — use it, modify it, teach with it, no strings attached.