TabOnce by dorian

TabOnce keeps duplicate tabs under control without affecting every page you visit.

Create opt-in rules for the websites and URL patterns that should only have one matching tab open. When TabOnce detects a duplicate, it closes the new tab and focuses the existing one instead.

Rules can:
- Match literal or variable path segments
- Treat deeper paths as the same page
- Include or ignore query strings and fragments
- Be enabled, disabled, and reordered
- Optionally intercept same-site links when the destination is already open

For example, different views of the same GitHub pull request can share one tab, while separate pull requests remain distinct.

Site access is requested separately for each configured origin. TabOnce is fully open-source, and does not collect or transmit any personal data.

Review the full source code at https://github.com/dkarter/tab-once