# GoogleChromeLabs/browser-fs-access

File System Access API with legacy fallback in the browser

Repository: https://github.com/GoogleChromeLabs/browser-fs-access
Canonical: https://ross.abutalabs.com/products/browser-fs-access
Homepage: https://googlechromelabs.github.io/browser-fs-access/demo/
Language: JavaScript
License: Apache-2.0
License Family: permissive
Topics: file-system-access, file-system-access-api, browser-fs-access
Last push: 2026-06-22T09:37:39+00:00

## Health v2 (maintenance only)
Score: 74/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 88, release rhythm 40, longevity 100
- inputs: {"age_days": 2394, "days_push": 72, "days_rel": 441, "gap_med": 27.0, "n_releases_24m": 3}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1581, forks 98 (observed 2026-08-28T04:05:07.009852+00:00)

## What it is
A JavaScript ponyfill library that provides the File System Access API on supporting browsers with a transparent fallback to legacy <input type="file"> and <a download> methods. It lets web apps open, save, and read files and directories through a single unified API regardless of browser support.

## Use cases
- open files in the browser with a unified api
- save files to disk from a web app
- read all files in a directory from the browser
- use file system access api with fallback for older browsers
- feature-detect file system access api support
- open multiple files with mime type filters in javascript
- stream a response or promise blob to a file download

## When to choose
- You need file open/save/directory access in a web app that must work across browsers, including ones without the File System Access API
- You want progressive enhancement: native File System Access API where available, legacy input/download fallbacks elsewhere
- You need to open files or directories with MIME/extension filtering through a small, tree-shakeable module

## When to avoid
- You are building a Node.js or server-side application rather than a browser app
- You only target browsers that fully support the File System Access API and don't need a fallback
- You need low-level filesystem operations like writing to arbitrary paths without user interaction

## Facets
- artifact type: library
- maturity: active
- function: file-system, file-upload, sdk
- domain: web-development, frontend, files, cross-platform
- platform: browser
- tags: file-system-access-api, ponyfill, progressive-enhancement, file-open, file-save, directory-open, browser-api, fallback, javascript, nodejs

## Member repositories
- GoogleChromeLabs/browser-fs-access (main) score 74

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:05:07.009852+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T03:56:20.986879+00:00, confidence not recorded.
  - readme: https://github.com/GoogleChromeLabs/browser-fs-access (fetched 2026-08-28T04:05:07.009852+00:00, sha bc1327946923)
  - homepage: https://googlechromelabs.github.io/browser-fs-access/demo/ (fetched 2026-08-29T11:26:46.015039+00:00, sha 646006189b53)
  - registry_npm: https://registry.npmjs.org/browser-fs-access (fetched 2026-08-29T11:26:46.017556+00:00, sha 362a1c3627a2)
- Data as of 2026-08-30T08:39:29.467469+00:00.