Mxlit

Mxlit is a lightweight, pure-Python alternative to Streamlit, powered by FastAPI and HTMX. It allows you to build interactive web applications by writing simple top-to-bottom Python scripts, without having to write any HTML, CSS, or JavaScript.

Features

• No Frontend Code Required: Write only Python.
• Fast and Lightweight: Uses HTMX for seamless partial page reloads instead of heavy React bundles and Websockets.
• State Management: Built-in session_state to persist data across interactions.
• Rich Components: Support for text, markdown, dataframes, metrics, images, and interactive widgets (buttons, text inputs, sliders, checkboxes).
• Layouts: Organize your app using sidebars, columns, tabs, and expanders.
• Advanced UI: Includes Named Entity Recognition (NER) highlighting and streaming text out of the box.

Installation

Install Mxlit via pip:

pip install mxlit

Quick Start

Create a file named app.py:

import mxlit as mt

mt.title("Hello Mxlit!")
mt.write("This is a simple interactive application.")

if "counter" not in mt.session_state:
    mt.session_state["counter"] = 0

if mt.button("Click me!"):
    mt.session_state["counter"] += 1

mt.write("Button clicked:", mt.session_state["counter"], "times")

Run your application using the Mxlit CLI:

mxlit run app.py

By default, the server will start at http://127.0.0.1:8501.

You can specify a custom host or port:

mxlit run app.py --host 0.0.0.0 --port 8000

How It Works

Mxlit executes your Python script top-to-bottom on every interaction. Behind the scenes:

1. The mxlit CLI spins up a FastAPI server.
2. The UI is dynamically generated as an HTML tree using Jinja2 templates.
3. User interactions (clicks, text input, slider changes) trigger HTMX POST requests to the server.
4. The server updates session_state, re-runs the Python script, and responds with only the HTML fragments that need to be updated.

External API Interactions

Because Mxlit applications are powered by a standard FastAPI server, you can directly interact with the application's global state from external sources using simple HTTP POST requests.

The /interact API

The /interact POST endpoint is typically used by the HTMX frontend to submit user interactions. However, you can call it manually (e.g., via webhooks or external scripts) by sending URL-encoded form data. The server updates the session_state, re-runs the Python script, and responds with the newly rendered HTML fragment.

The /modify API (Real-time Broadcasts)

The /modify POST endpoint allows external systems or background workers to update the app's state and instantly push the updated UI to all currently connected browsers in real-time using Server-Sent Events (SSE). It returns a JSON status response, making it perfect for headless automation or IoT integrations.

curl -X POST http://127.0.0.1:8501/modify \
  -H "Content-Type: application/x-www-form-urlencoded" \
  -d "counter=100"

Advanced Usage

Mxlit supports many of the patterns you know and love:

import mxlit as mt
import pandas as pd

# Layouts
with mt.sidebar:
    mt.header("Settings")
    rows = mt.slider("Rows to show", 1, 10, 5)

col1, col2 = mt.columns(2)
with col1:
    mt.metric("Users", 1024, "+12%")

# Dataframes
df = pd.DataFrame({"A": range(rows), "B": range(rows)})
mt.dataframe(df)

# Text Streaming
def my_stream():
    for word in ["Streaming ", "text ", "is ", "cool!"]:
        yield word
mt.write_stream(my_stream())