Dash

Dash is an open-source Python framework from Plotly for building analytical, data-driven web applications. Data scientists and engineers write the whole app in Python, with no HTML, CSS, or JavaScript: Dash runs on Flask on the server, renders React components in the browser, and draws charts with Plotly.js.

The core idea is the callback. A Python function is declared with the component properties it reads as inputs and the ones it updates as outputs, and Dash calls it whenever an input changes, so a dropdown, slider, or table selection can re-filter data and redraw a chart. Pattern-matching and client-side callbacks cover dynamic layouts and interactions that should not wait for the server, and background callbacks run long jobs without blocking the app.

Apps are assembled from component libraries: Dash Core Components (dropdowns, sliders, date pickers, uploads), the Dash DataTable and AG Grid for sortable, editable tables, HTML components, and community libraries such as Dash Bootstrap Components and Dash Mantine Components. Built-in multi-page routing and a hot-reloading dev server round it out. Dash is common in finance, pharma, and engineering for internal analytics tools.

The framework is free under the MIT license and can be deployed anywhere a Python web app runs. Plotly Cloud adds one-click publishing from Dash with private viewers and custom domains, with a free plan and a paid Pro plan per creator seat, and Plotly Enterprise (formerly Dash Enterprise) adds SSO, self-managed hosting, and the Dash Design Kit through sales.