Mesop: Build delightful web apps quickly in Python 🚀

[!WARNING] Mesop is no longer maintained as of September 30, 2026. No further updates, bug fixes, or support will be provided.

• If you're interested in learning how to use Mesop, please read our main docs.

• If you're interested in contributing to the core Mesop framework, please read our contributing guide.

Used at Google for rapid internal app development

Mesop is a Python-based UI framework that allows you to rapidly build web apps like demos and internal apps:

Intuitive for UI novices ✨

• Write UI in idiomatic Python code
• Easy to understand reactive UI paradigm
• Ready to use components

Frictionless developer workflows 🏎️

• Hot reload so the browser automatically reloads and preserves state
• Rich IDE support with strong type safety

Flexible for delightful demos 🤩

• Build custom UIs without writing Javascript/CSS/HTML
• Compose your UI into components, which are just Python functions

Write your first Mesop app in less than 10 lines of code...

Demo app

import mesop as me
import mesop.labs as mel


@me.page(path="/text_to_text", title="Text to Text Example")
def app():
  mel.text_to_text(
    upper_case_stream,
    title="Text to Text Example",
  )


def upper_case_stream(s: str):
  return "Echo: " + s.capitalize()

Try it

Colab

You can try Mesop on Colab!

Locally

Step 1: Install it

pip install mesop

Step 2: Copy the example above into main.py

Step 3: Run the app

mesop main.py

Learn more in Getting Started.

Reporting a security issue

If you identify a security vulnerability with Mesop, please file a GitHub security issue and we will promptly respond to it.

Disclaimer

This is not an officially supported Google product.