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Circadian

github.com/Pasithea0/circadian-extension Browser Extensions Open-source projectOpen source

Tint webpage colors by time of day with Circadian, a browser extension offering daytime, sunset, and bedtime settings.

Visit Circadian 24 alternatives
github.com/Pasithea0/circadian-extension
Circadian homepage screenshot

About Circadian

Circadian is an open-source browser extension that adjusts webpage color tints based on time of day, with three presets: daytime, sunset, and bedtime. It was created to reduce blue light exposure from screens, which can disrupt the body's natural circadian rhythm by interfering with melanopsin receptor function, and is inspired by the discontinued f.lux iOS app.

The extension works by placing an invisible overlay on web pages and applying a calculated CSS filter to tint content. It is compatible with Chrome and Firefox desktop browsers, and can also be installed on iOS via the Orion browser. Users can pair Circadian with existing dark mode extensions for enhanced comfort, and the project is hosted publicly on GitHub under an MIT license for community contributions.

Key features

  • Time-based webpage tinting with daytime, sunset, and bedtime presets
  • Reduces blue light exposure to support natural circadian rhythm
  • Compatible with Chrome, Firefox, and iOS Orion browser
  • Can be paired with other dark mode browser extensions
  • Open source under MIT license for community modification
Best for: It is best suited for users seeking to reduce screen blue light exposure to support their circadian rhythm and sleep quality, including former f.lux iOS users and those who want to pair a tinting tool with existing dark mode extensions.
Good for
  • Open-source tool with publicly accessible source code
  • Lightweight design that works alongside existing dark mode extensions
  • Supports multiple platforms including iOS via Orion browser
  • Simple setup with minimal configuration required
Watch out for
  • Only tints web pages, not system-wide screen content
  • Less polished than dedicated tools like f.lux
  • Requires permission to modify all visited websites

Circadian at a glance

Type
Open-source project
Pricing
Not confirmed. Check the site
Platforms
Browser extension, iOS
Open source
Yes · Source code
Language
English
Last checked
Oct 5, 2026 · Online when checked
Listed
Oct 5, 2026
open sourceiosbrowser extensiondark mode

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Circadian FAQ

What does the Circadian browser extension do?
Circadian adjusts webpage color tints based on time of day to reduce blue light exposure, with daytime, sunset, and bedtime presets.
Does Circadian work on iOS devices?
Yes, Circadian can be installed on iOS via the Orion browser, as an alternative to the discontinued f.lux iOS app.
Can I use Circadian with other dark mode extensions?
Yes, the developer recommends pairing Circadian with existing dark reader extensions for improved browsing comfort.
Is Circadian open source?
Yes, Circadian is hosted on GitHub under the MIT license, with its full source code publicly available.
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Listing maintained by Chris McClure and the WebIndexly editors · Updated Oct 7, 2026 · How we rank