pyrepl-web

An embeddable Python REPL, powered by Pyodide.

Live demo

Getting started

Include the script and use the web component:

``html



`

That's it! No install needed.

Features

- 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

Attributes

| Attribute | Description | Default |
|-----------|-------------|---------|
| theme | Color theme name (builtin or registered via window.pyreplThemes) | catppuccin-mocha |
| packages | Comma-separated list of PyPI packages to preload | none |
| repl-title | Custom title in the header bar | Python REPL |
| src | Path to a Python startup script (see below) | none |
| no-header | Hide the header bar (boolean attribute) | not set |
| no-buttons | Hide copy/clear buttons in header (boolean attribute) | not set |
| readonly | Disable input, display only (boolean attribute) | not set |
| no-banner | Hide the "Python 3.13" startup banner (boolean attribute) | not set |

$3

Use src to preload a Python script that sets up the environment:

`html

`

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

`python


setup.py

def setup():
print("DataFrame loaded:")
print(df)
`

$3

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

#### Custom Themes

Register custom themes via window.pyreplThemes before loading the script. Only background and foreground are required - everything else is automatically derived:

`html




`

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

#### Theme Properties

| Property | Description |
|----------|-------------|
| background | Terminal background color (required) |
| foreground | Default text color (required) |
| headerBackground | Header bar background (optional) |
| headerForeground | Header title color (optional) |
| promptColor | Prompt >>> color - hex (#7aa2f7) or name (green, cyan) (optional) |
| pygmentsStyle | Custom syntax highlighting (optional, see below) |

#### Syntax Highlighting

Syntax highlighting uses Pygments. The style is chosen automatically:

1. If your theme name matches a Pygments style (e.g., monokai, dracula), that style is used
2. Otherwise, uses catppuccin-mocha for dark backgrounds or catppuccin-latte for light backgrounds

For full control, provide a pygmentsStyle mapping Pygments tokens to colors:

`html

``