cacao 2.0.9

High-performance reactive web framework for Python. Build dashboards, internal tools, and data apps with a Streamlit-like API but 10x faster.

Cacao

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High-performance reactive web framework for Python. Build dashboards, internal tools, and data apps with a simple API — 10x faster than Streamlit with true WebSocket reactivity.

v2.0 - Complete rewrite with signal-based reactivity, session-scoped state, and a Streamlit-like API that doesn't re-run your entire script.

Quick Start

pip install cacao

Hello World (4 lines)

import cacao as c

c.title("Hello, Cacao!")
c.text("Welcome to the simplest Python web framework")

Interactive Counter

import cacao as c

c.config(title="Counter")

count = c.signal(0, name="count")

@c.on("increment")
async def increment(session, event):
    count.set(session, count.get(session) + 1)

@c.on("decrement")
async def decrement(session, event):
    count.set(session, count.get(session) - 1)

c.title("Counter")

with c.card():
    c.metric("Count", count)
    with c.row():
        c.button("-", on_click="decrement", variant="secondary")
        c.button("+", on_click="increment")

Dashboard with Charts

import cacao as c

c.config(title="Sales Dashboard", theme="dark")

sales = c.sample_sales_data()

c.title("Sales Dashboard")

with c.row():
    c.metric("Revenue", "$45,231", trend="+20.1%", trend_direction="up")
    c.metric("Orders", "1,247", trend="+12.5%", trend_direction="up")
    c.metric("Customers", "842", trend="+5.3%", trend_direction="up")

with c.row():
    with c.col(span=8):
        with c.card("Revenue Trend"):
            c.line(sales, x="date", y="revenue", area=True)
    with c.col(span=4):
        with c.card("By Category"):
            c.pie(sales[:5], values="revenue", names="category", donut=True)

with c.card("Recent Transactions"):
    c.table(sales[:10], columns=["date", "category", "revenue", "orders"])

Run with:

cacao run dashboard.py

Why Cacao?

Feature	Cacao	Streamlit
Reactivity	Signal-based (only changed values update)	Full script re-run on every interaction
State	Session-scoped by design	st.session_state bolt-on
Updates	WebSocket streaming (instant)	HTTP polling (laggy)
Multi-user	Isolated sessions built-in	Shared state issues
API	Context managers + decorators	Magic globals

Core Concepts

Signals (Reactive State)

count = c.signal(0, name="count")

# Get value for a session
current = count.get(session)

# Set value (auto-syncs to client)
count.set(session, current + 1)

Event Handlers

@c.on("submit")
async def handle_submit(session, event):
    print(event.get("value"))

Layout Components

with c.row():           # Horizontal layout
    with c.col(span=8): # 8/12 width column
        c.text("Main content")
    with c.col(span=4): # 4/12 width column
        c.text("Sidebar")

with c.card("Title"):   # Card container
    c.metric("Value", 100)

with c.tabs():          # Tabbed content
    with c.tab("tab1", "First"):
        c.text("Tab 1 content")
    with c.tab("tab2", "Second"):
        c.text("Tab 2 content")

Form Components

c.button("Click me", on_click="submit")
c.input("Name", signal=name_signal)
c.select("Category", ["A", "B", "C"])
c.checkbox("Agree", signal=agree_signal)
c.slider("Volume", min=0, max=100)

Charts

c.line(data, x="date", y="value")
c.bar(data, x="category", y="count")
c.pie(data, values="amount", names="label")
c.area(data, x="date", y="value")
c.scatter(data, x="x", y="y")
c.gauge(value=75, max_value=100)

Architecture

┌─────────────────────────────────────────────────────────────────┐
│                         PYTHON SERVER                            │
│  ┌──────────┐  ┌──────────┐  ┌──────────┐  ┌───────────────┐   │
│  │ Signals  │  │ Sessions │  │  Events  │  │ WebSocket/HTTP│   │
│  │ (state)  │──│ (per-    │──│ (typed   │──│    Server     │   │
│  │          │  │  client) │  │  async)  │  │               │   │
│  └──────────┘  └──────────┘  └──────────┘  └───────┬───────┘   │
└────────────────────────────────────────────────────┼───────────┘
                                                     │ JSON
                                                     │ WebSocket
┌────────────────────────────────────────────────────┼───────────┐
│                      REACT CLIENT                   │           │
│  ┌──────────┐  ┌──────────┐  ┌──────────┐  ┌──────┴──────┐    │
│  │  Hooks   │  │Components│  │  Event   │  │   State     │    │
│  │useCacao()│──│ (your UI)│──│Dispatcher│──│   Store     │    │
│  └──────────┘  └──────────┘  └──────────┘  └─────────────┘    │
└─────────────────────────────────────────────────────────────────┘

Project Structure

cacao/
├── __init__.py          # Simple API exports
├── simple.py            # Streamlit-like API
├── server/              # Core server
│   ├── app.py           # App class
│   ├── signal.py        # Signal, Computed
│   ├── session.py       # Session management
│   ├── events.py        # Event handling
│   ├── server.py        # WebSocket server
│   ├── ui.py            # UI components
│   ├── chart.py         # Chart components
│   └── data.py          # Data utilities
├── cli/                 # CLI commands
└── examples/            # Example apps

CLI

# Run an app with hot reload
cacao run app.py

# Run on custom port
cacao run app.py --port 3000

# Create a new project
cacao create my-dashboard

# Build a static site (no server required)
cacao build app.py

# Build for GitHub Pages subdirectory
cacao build app.py --base-path /my-repo

Static Builds

Cacao can generate static sites that run entirely in the browser — no Python server required. Perfect for GitHub Pages, Netlify, or any static hosting.

cacao build app.py

This creates a dist/ folder with:

• index.html - Your app
• cacao.js - Runtime with built-in handlers
• cacao.css - Styles

Built-in handlers for common operations work automatically:

• Encoders: Base64, URL, HTML entities, JWT decode
• Generators: UUID, passwords, Lorem Ipsum
• Converters: JSON/YAML, case conversion, number bases
• Text: Statistics, regex testing
• Crypto: Hash generation, HMAC

Deploy to GitHub Pages:

# .github/workflows/deploy.yml
- run: pip install cacao
- run: cacao build app.py --base-path /${{ github.event.repository.name }}

See cacao-tools for a full static site example.

Examples

See the examples/ directory:

• examples/simple/hello.py - Minimal app
• examples/simple/counter.py - Interactive counter
• examples/simple/metrics.py - KPI dashboard
• examples/simple/dashboard.py - Full dashboard with charts

Contributing

Contributions are welcome! Please read our contributing guidelines for details.

License

MIT