AlphaFonts Font Inspector by AlphaFonts Font Inspector

AlphaFonts Font Inspector shows you the typography behind any webpage in seconds.

HOW IT WORKS

Click the AlphaFonts button (or press Alt+Shift+F) and choose "Start Inspecting".
Hover over any text to see its font, size, weight, line height, letter spacing and color.
Click to lock the panel, then copy the CSS, a plain-text summary, or the element's selector.
WHAT YOU GET

Font family stack, size, weight, style, line height, letter and word spacing, alignment, transform, decoration and color (HEX or RGB, transparency kept).
"Label all text on page": a small label above every text element showing the properties you choose.
Live editing: try a new size, weight, color and more on the page, with sliders and px / rem / em / unitless converters.
Contrast checker with WCAG AA and AAA results and a one-click suggested passing color.
"Copy changes" copies only what you edited. Every edited field has its own undo.
Choose which properties to show, copy, and label. Light and dark themes.
Right-click menu, keyboard shortcut, and an options page.
PRIVATE BY DESIGN Everything runs on your computer. The extension collects no data, makes no network requests, has no accounts and no analytics. Your settings (theme and chosen properties) are stored locally in your browser. Source code is plain, readable JavaScript.

NOTES

It cannot run on Firefox's own pages or on addons.mozilla.org (a Firefox rule for all extensions).
Only the main page is inspected; text inside iframes is not.
Made by AlphaFonts: https://alphafonts.com