# OPFS + Pyodide test harness

> Source: <https://simonwillison.net/2026/Jun/23/opfs-pyodide/#atom-everything>
> Published: 2026-06-23 18:58:54+00:00

**Tool:** [OPFS + Pyodide test harness](https://tools.simonwillison.net/opfs-pyodide)

I've been pondering if [Datasette Lite](https://lite.datasette.io/) - the Python Datasette application run entirely in the browser using Pyodide and WebAssembly - might be able to edit persistent SQLite files stored on the user's computer.

That's what [OFPS](https://developer.mozilla.org/en-US/docs/Web/API/File_System_API/Origin_private_file_system) (Origin Private File System) is for, so I had Claude Code for web build me this playground UI to try it out in different browsers.

Tags: [browsers](https://simonwillison.net/tags/browsers), [pyodide](https://simonwillison.net/tags/pyodide), [datasette-lite](https://simonwillison.net/tags/datasette-lite)