TabShade by Marc Fearby

TabShade dims the current tab with an adjustable overlay to reduce brightness and ease eye strain in dark or low-light settings. Shade every site by default at a level you choose, or save custom levels for specific sites. Adjust on the fly with keyboard shortcuts.

Key features:

• Shade by default — pick a default level and every site is dimmed to it automatically, without cluttering your saved-sites list.
• Per-site levels — save a custom shade level for individual sites you want to treat specially. Only sites you explicitly save are remembered.
• Keyboard shortcuts — more dim (Alt+Shift+↑), less dim (Alt+Shift+↓), and toggle shading (Alt+Shift+D), all rebindable.
• Toolbar badge — the active tab's shade level shows right on the toolbar icon at a glance.
• Preferences page — review, adjust, or remove every site you've saved, with a light or dark popup theme.
• Ignore dark sites (experimental) — optionally skip pages that already use a dark background, so you're not double-dimming them.

Your settings and saved sites stay on your device using Firefox's local storage. TabShade collects no data and requires no account.