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Preswald

Preswald is a Python tool for building interactive data apps and packaging their code, data and interface into browser-run applications. Its WebAssembly-based stack includes Pyodide and DuckDB, with Pandas, Plotly and Matplotlib also named by the project.

Explore the practical guide ↓

Independent OpenViST project profile, based on linked sources.

Preswald — OpenViST project profile in AI Data & Analytics.
OpenViST project illustration. See the linked sources for product details.
Understand the project

Practical overview

When it fits

Use Preswald when you want to build a Python data interface and package it for browser use, particularly when a self-contained file or offline workflow is useful.

Who it is for

  • Python developers building data applications.
  • Analysts creating dashboards and interactive reports.
  • Teams sharing data tools with people who should not need to install the app's local dependencies.
  • Users packaging data workflows for offline or local browser use.

Documented uses

  • Build an interactive dashboard or report with Python.
  • Package visualizations and data workflows into a shareable app.
  • Create a browser-based tool for inspecting files, logs or snapshots.
  • Prepare an offline data application for fieldwork or secure environments.
Before you choose

Requirements & limits

  • The documented development workflow uses Python and a project entry point such as hello.py.
  • The runtime is based on WebAssembly, Pyodide and DuckDB; the repository also names Pandas, Plotly and Matplotlib.
  • Static export creates a dist/ folder described as usable locally, shareable as a folder or embeddable in hosting platforms.
  • The project identifies Apache-2.0 as its license.

Check current requirements in the official documentation. Source-based guidance does not mean OpenViST has run or independently tested this project.

Source-based practical guide

Set up and run a local Preswald app

Create a starter project and launch it for local development.

Before you start

  • Python 3.7 or later, as indicated by the repository README.
  • The Preswald Python package.

Steps

  1. Install the package with the command below.

    Documented command
    pip install preswald

  2. Run preswald init my_app to create a project.

  3. Change into the project directory and edit hello.py to define the app.

  4. Run preswald run to launch the development server.

Expected outcome

A starter app runs from a local development server, which the README says typically uses `http://localhost:8501`.

Guide limitations

  • The repository describes this as a local development workflow; it does not document this step as a deployment method.
Documentation 1 ↗
Source-based practical guide

Export an app as a static site

Package an existing Preswald app into a static output folder for local use or sharing.

Before you start

  • A Preswald app project.

Steps

  1. From the project, run preswald export.

  2. Use the generated dist/ folder, which the README describes as containing the files needed to run the app locally or share it.

Expected outcome

A static app package containing the Python code, data and DuckDB queries, with the interface, logic and reactive state preserved according to the README.

Guide limitations

  • The README describes local browser use, folder sharing and embedding in hosting platforms; it does not give hosting-provider-specific instructions.
Documentation 1 ↗
Evidence and transparency

Sources & review

Official repository ↗
Source record details
Source availability
Active
Sources checked
7 October 2026
Original website title
StructuredLabs/preswald · Official homepage title · retained in its source language
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