Compatibility

What works, what partially works, and what the browser forbids.

Browsers

  • Chrome: fully supported (primary target).
  • Edge: supported (Chromium-based).
  • Firefox: supported via the Firefox build.

Works

  • Articles, docs, and feeds, including content loaded by scrolling or navigation without reload.
  • Inputs, textareas, and placeholders.
  • Rich-text editors (Gmail compose, social posts, chat boxes).
  • React/Vue and other dynamic apps. Replacement re-applies as the page updates.
  • Pages inside frames (same-origin and cross-origin).
  • Open shadow-DOM components (e.g. many web-component widgets).

Known limitations

  • Browser-reserved pages (chrome://, edge://, the Chrome Web Store page) forbid content scripts entirely.
  • file:// pages need “Allow access to file URLs” enabled for the extension in chrome://extensions.
  • Closed shadow roots are unreadable by design. No extension can reach inside them.
  • Canvas-rendered text and images of text can't be replaced (there is no DOM text to change).
  • Inputs are processed unless a rule ignores them. There is no automatic skipping by input type. Use ignore selectors or site scopes for sensitive fields and editors.

Found a site that misbehaves?

See Troubleshooting first, then tell us the site so we can improve compatibility.