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An embeddable Python REPL, powered by Pyodide.

Live demo

Include the script and use the<py-repl> web component:

<scriptsrc="https://cdn.jsdelivr.net/npm/pyrepl-web/dist/pyrepl.js"></script><py-repl></py-repl>

That's it! No install needed.

• Python 3.13 in the browser via WebAssembly (Pyodide)
• Syntax highlighting powered by Pygments
• Tab completion for modules, functions, and variables
• Command history with up/down arrows
• Smart indentation for multi-line code
• Keyboard shortcuts: Ctrl+L (clear), Ctrl+C (cancel)
• PyPI packages: preload popular libraries
• Startup scripts: run Python on load to set up the environment
• Theming: built-in dark/light themes or fully custom

Usesrc to preload a Python script that sets up the environment:

<py-replsrc="/scripts/setup.py"packages="pandas"></py-repl>

The script runs silently to populate the namespace. If you define asetup() function, it will be called after loading and its output is visible in the terminal:

# setup.pyimportpandasaspddf=pd.DataFrame({'name': ['Alice','Bob'],'age': [30,25]})defsetup():print("DataFrame loaded:")print(df)

Built-in themes:catppuccin-mocha (dark, default) andcatppuccin-latte (light).

Register custom themes viawindow.pyreplThemes before loading the script. Onlybackground andforeground are required - everything else is automatically derived:

<script>window.pyreplThemes={'my-theme':{background:'#1a1b26',foreground:'#a9b1d6',}};</script><scriptsrc="https://cdn.jsdelivr.net/npm/pyrepl-web/dist/pyrepl.js"></script><py-repltheme="my-theme"></py-repl>

What gets auto-derived from your background color:

• Terminal colors (red for errors, green for success, etc.) - from catppuccin-mocha (dark) or catppuccin-latte (light)
• Syntax highlighting - uses the matching catppuccin Pygments style
• Header colors - derived from the base theme

Syntax highlighting usesPygments. The style is chosen automatically:

1. If your theme name matches aPygments style (e.g.,monokai,dracula), that style is used
2. Otherwise, usescatppuccin-mocha for dark backgrounds orcatppuccin-latte for light backgrounds

For full control, provide apygmentsStyle mappingPygments tokens to colors:

<script>window.pyreplThemes={'tokyo-night':{background:'#1a1b26',foreground:'#a9b1d6',promptColor:'#bb9af7',pygmentsStyle:{'Keyword':'#bb9af7','String':'#9ece6a','Number':'#ff9e64','Comment':'#565f89','Name.Function':'#7aa2f7','Name.Builtin':'#7dcfff',}}};</script>