filesystem.online

This page explains what filesystem.online is, how to use it, and what to know about privacy, writable mode, read-only snapshots, offline usage and donations.

Overview

filesystem.online is a single-page, standalone web app that lets you browse and manage local files and folders directly in your browser. It provides a tree view, multiple listing modes and inline previews for common file types.

Local only: your files never leave your device.
No install required: just open the HTML file in a modern browser.
Optional write access: create, rename, delete and save files in writable mode.
Works offline: you can save the page and use it without internet access.
Donationware: free to use; consider supporting via PayPal, Ko-fi or Buy Me a Coffee.

Privacy & Security

Nothing is sent to any server. The viewer runs fully in your browser (client-side only). When you select a folder, the browser grants the page access to that folder for the current session. The app:

does not upload or sync files;
does not use analytics or tracking pixels;
does not store your files beyond the current session (object URLs live only in memory).

If you refresh or close the page, access to your folder is revoked by the browser and has to be granted again next time.

Writable mode vs Read-only snapshots

Open Folder (writable): uses the File System Access API. Supported by Chrome, Edge and a few other modern browsers. In this mode you can:
- Create new files and folders.
- Rename and delete entries.
- Edit text files and save changes back to disk.
Open Read-only: works in more browsers. You pick a set of files and folders as a snapshot. You can:
- Browse the structure and see previews.
- Download individual files.
- But you cannot modify, rename or delete anything.

Using It Offline (Saving the App)

Open the viewer in your browser.
Save the page as a single HTML file:
- Windows/Linux: press Ctrl+S, choose a location, keep the .html extension.
- macOS: press Cmd+S.
Later, open that saved HTML file directly in your browser (double-click). You can use the viewer completely offline.

Both writable and read-only modes depend on what your browser supports. Offline behaviour is the same: everything stays local.

Browser Support

Best experience: recent versions of Chromium-based browsers (Chrome, Edge, Brave, etc.).
Writable mode: requires support for the File System Access API.
Read-only mode: works in most modern browsers, but some details may differ.
Mobile browsers: may impose additional restrictions on file access.

How to Use

Choose Open Folder for writable access, or Open Read-only for a snapshot.
Use the left tree to expand folders and select the location you want to inspect.
In the main area, switch between Thumbs, List and Details view.
Click a file to preview it or open it in the built-in editor (for supported text formats).
Use the toolbar actions (New, Rename, Delete, Save, Download) depending on the current mode.

Key Features

Tree navigation: quickly jump between folders with a familiar sidebar.
Multiple views: Thumbs, List and Details with sortable columns.
Inline previews: images, video, audio and PDFs directly inside the page.
Text editor: edit common text-based formats and save changes in writable mode.
Keyboard shortcuts: efficient navigation and file operations.

Keyboard Shortcuts

F2 - Rename selected file or folder (writable mode).
Ctrl/Cmd + S - Save in the text editor (writable mode).
Shift + Delete - Delete selected entry (writable mode).
Shift + D - Download selected file.
Arrow Left / Right - Previous / next file in the current folder.
F - Toggle fullscreen for the viewer/editor area.

Donationware

The app is free to use. If it saves you time or fits into your workflow, please consider supporting the project. Thank you!

Troubleshooting Checklist

Buttons disabled? Check whether you are in read-only mode or using an unsupported browser.
Nothing happens when opening a folder? Verify that your browser allows file system access.
Previews broken? Try with a smaller test folder or a different browser.
Files missing? Remember that the app only sees the folder you explicitly selected.

Credits

filesystem.online is an independent project that uses modern browser APIs to provide a lightweight, local-first file manager experience. It is designed for personal and non-critical workflows; always keep your own backups of important data.