Plainly от 27mfp

Plainly finds Base64-style coded text on web pages and shows the readable version next to it.

What it does
- Works automatically on Reddit
- Add any other site from the toolbar menu (permission only when you allow it)
- If the decoded text is a link, you can open it
- Copy plain text with one click
- Manual “Try a code” box in the popup
- On/off switch

How to use
1. Install and open Reddit (or add another site)
2. Refresh the tab
3. Look for grey tags next to coded strings

Privacy
Everything runs locally in your browser. Nothing is sent to any server — no analytics, accounts, or remote decode API.

Source: https://github.com/27mfp/plainly