Stop Autofill

A Chromium-based browser extension that gives you control over autofill behavior on websites.

Features

• Opt-in control: Only affects sites/pages you explicitly enable
• Granular rules: Block autofill for entire sites, specific pages, or individual elements
• Element picker: AdBlocker-style picker to block specific form fields
• Password manager control: Discourage password manager suggestions (gentle approach)
• Privacy-focused: Never stores your form data, only stores rules and selectors

How It Works

Rule Scopes

The extension supports three levels of rules (in order of priority):

1. Element rules (most specific) - Block specific form fields using CSS selectors
2. Page rules - Apply to a specific URL
3. Site rules - Apply to an entire origin (e.g., all pages on example.com)

Usage

From the Popup Panel

1. Click the extension icon to open the panel
2. Toggle "This website" to enable/disable for the entire site
3. Toggle "This page" to enable/disable for just the current page
4. Toggle individual features (AutoFill, Password Manager)

Block Specific Elements

1. Right-click on the page → "Stop Autofill: Block element…"
2. Click on the form field you want to block
3. Choose scope (site or page) and features to disable
4. Click "Save & Apply"

Installation

Development Install

1. Download/clone this repository
2. Open Chrome/Edge and go to chrome://extensions/
3. Enable "Developer mode" (top right)
4. Click "Load unpacked"
5. Select the extension directory

How Suppression Works

The extension uses gentle, best-effort techniques:

• Disable AutoFill: Sets autocomplete="off" on forms and inputs
• Disable Password Manager: Sets autocomplete="new-password" on password fields and autocomplete="off" on username-like fields

Note: Some sites may fight back against these attributes. This is a gentle approach that works with most sites but isn't foolproof.

Privacy & Storage

What Gets Synced (chrome.storage.sync)

• All rules (site/page/element)
• User preferences
• Total forms blocked counter

If you have Chrome Sync enabled, these settings will sync across your devices.

What Doesn't Get Synced

• Per-page counters (session storage only)
• Temporary picker state

What Never Gets Stored

• Form values
• Autofill data
• Passwords
• Any typed text

Only stores: origins, URLs, CSS selectors, and feature flags.

Development

File Structure

stopautofill/
├── manifest.json          # Extension manifest
├── sw.js                  # Service worker (background script)
├── content/
│   ├── apply.js           # Content script that applies rules
│   ├── picker.js          # Element picker functionality
│   └── picker.css         # Picker UI styles
└── ui/
    ├── panel.html/css/js  # Popup panel
    └── confirm.html/css/js # Element block confirmation

Key Technologies

• Manifest V3
• chrome.storage.sync for settings
• chrome.storage.session for temporary data
• MutationObserver for dynamic content

Known Limitations

• Some sites actively fight autocomplete suppression
• Can't truly disable browser password managers (only discourage)
• Requires page refresh for changes to take effect
• Element selectors may break if sites change their HTML

Website

stopautofill.com

License

GPL-3.0 - See LICENSE file for details

Contributing

This is a personal project but suggestions and bug reports are welcome!