Chrome theme editor

Design a browser theme against a live preview, then export it as an extension you can load in Chrome or package for Firefox.

• Start from a preset, from a seed color, or from a wallpaper image.
• Set colors, HSL tints, and images for the frame, toolbar, tab strip, and new tab page.
• Read contrast checks on the text and background pairs the theme sets.
• Import an existing theme from a manifest.json, a theme ZIP, or a Chrome Web Store CRX.
• Export an unpacked folder, a manifest.json, a ZIP package, or a Firefox package.

A Chrome theme is an extension whose manifest carries a theme block, so the export loads the way any unpacked extension does: turn on Developer mode in chrome://extensions and choose Load unpacked. The preview stays Chrome, and nothing here shows how Firefox will paint the theme.