Dark Reader vs NightOwl: Choosing a Firefox Dark Mode Extension

Dark Reader and NightOwl are two popular Firefox extensions for enabling dark mode on web pages. Dark Reader has been around since 2014 and boasts over 5 million users, making it the default recommendation for browser-wide dark mode. It works by analyzing a page's CSS and generating a new dark theme, adjusting colors to maintain contrast and readability. It doesn't simply invert colors but rather understands what constitutes backgrounds, texts, and accents to apply them appropriately.

Dark Reader offers several strengths, including more sophisticated rendering, fine-grained per-site configuration (brightness, contrast, sepia, font), active development with frequent updates, and a large user base that has been well-tested across thousands of sites. It can also use Dynamic mode for even smarter per-site theming. However, it has some weaknesses like heavier processing, especially on complex pages, occasional rendering artifacts on unusual layouts, and more moving parts that can occasionally break.

On the other hand, NightOwl takes a simpler approach by applying a CSS filter: invert() to the entire page. This means images get double-inverted to look correct, resulting in a consistent dark appearance with minimal processing. Its strengths lie in its simplicity, predictable nature, per-domain toggle for enabling or disabling it on specific sites, lightweight nature with minimal memory and CPU overhead, and not requiring any configuration beyond the per-domain toggle.

However, NightOwl also has its weaknesses, such as photos and videos looking slightly washed out due to CSS inversion not being photographic, less sophisticated than Dark Reader's dynamic mode, and not adjusting contrast or brightness independently. When deciding which extension to use, consider the following factors. If you want the most visually polished result across all sites, have a need for fine-grained control per site, and don't mind the extra overhead, Dark Reader is the better choice.

If you prefer a simple, no-configuration option, mainly want dark mode for text-heavy sites, want minimal extension overhead, and already use other extensions to keep your extension footprint small, NightOwl would be more suitable. Both extensions address the same core problem, but Dark Reader is more capable, while NightOwl is a lighter option.

As a last resort, you can try Firefox's built-in setting: ui.systemUsesDarkTheme = 1, but it only works on sites that actually check this media query preference.