Why does Google change the color of URLs in the SERPs from green to gray?

What is the origin of these color variations in Google results?

Since the beginnings of Google, the color of URLs in the SERPs has served as a distinctive visual marker. Historically, green was the norm—a color choice that allowed clear differentiation between the web address, the blue title, and the black description.

In recent years, Google has ramped up interface testing, experimenting with gray URLs, sometimes in black, even going so far as to eliminate the visible display of the full URL in favor of showing only the domain name. Mueller's statement confirms what many have observed: these changes are part of ongoing A/B testing focused on user experience, not algorithmic changes.

Do these tests affect user behavior?

The color of an element in an interface can influence the click-through rate (CTR). A bright green catches the eye, while gray blends into the background. Google is likely measuring whether a less pronounced visual hierarchy changes how users scan the results.

Specifically, a gray URL could diminish the perceptual salience of this component, redirecting attention to the title and the snippet. Google tests the balance between transparency (showing the URL) and reducing visual noise that could distract from essential information. No public data exists on the results of these tests, but it can be assumed that Google is optimizing for user satisfaction measured through internal metrics.

Should an SEO be concerned about this?

No. The display color of the URL in the SERPs is purely cosmetic from an SEO perspective. It does not indicate a special status for the site, a penalty, or a ranking advantage.

Some professionals may have worried upon seeing their URLs turn gray, fearing a negative signal. Mueller's clarification puts these speculations to rest: these are user interface experiments deployed randomly or segmented based on criteria known only to Google (geography, query type, user profile). Your SEO work remains unchanged.

• Color variations (green/gray) are UX tests, not ranking signals.
• No direct impact on the ranking or indexing of your pages.
• These tests may slightly change the observed CTR if the URL's visibility changes.
• Google has never provided numerical data on the CTR impact of these variations.
• The structure of your URLs remains important for technical SEO (readability, keywords), regardless of their display color.

Is Mueller's explanation consistent with field observations?

Yes, largely. For several years, SEOs have noticed inconsistent display variations between users, browsers, or even between two identical searches made a few hours apart. These behaviors typically correspond to A/B testing deployments in production.

Google has a long-standing history of continuous experimentation with the SERP interface: the removal of full URLs in favor of breadcrumbs, the addition of site icons (favicons), adjustments to spacing, and changes to font sizes. The color of URLs fits into this logic. Notably, Mueller taking the time to clarify shows that enough professionals have raised the question for Google to see the value in dispelling the ambiguity.

What uncertainties remain in this statement?

Mueller remains vague on the criteria that determine which user sees which version. Does Google test based on query type (navigational vs informational)? By user profile (click history, behavior)? By site performance (speed, Core Web Vitals)? [To be verified] No data exists on this.

Similarly, there is no transparency regarding the results of these tests. Is Google measuring an improvement in CTR with gray? Better user satisfaction? Reduced decision-making time? In the absence of such data, it is difficult to anticipate whether a version will become standardized or if testing will continue indefinitely. Caution leads to the assumption that Google will continue to experiment without a definitive stabilization in the short term.

Could a color become an indirect signal?

Theoretically, if Google ever decided to associate a specific color with a quality label (for example, green for sites with HTTPS and good Core Web Vitals), this would become relevant. However, nothing in Mueller's statement suggests this direction.

On the contrary, he explicitly frames these variations as interface tests, not status indicators. Any contrary interpretation would be an over-analysis. If tomorrow Google introduces such a color labeling system, it will communicate it officially—as it did for HTTPS with the lock or for AMP with the lightning bolt (now discontinued).

What actions should be taken in response to these variations?

Nothing. Absolutely nothing in your SEO strategy should change because your URLs display as green or gray. This is not an actionable signal, just a visual element that you do not control.

Focus on what really matters: the structure of your URLs (short, descriptive, containing relevant keywords), their hierarchical consistency, and the relevance of your title tags and meta descriptions which do directly influence the CTR. The display color is outside your optimization scope.

What mistakes should be avoided in interpreting this signal?

Do not draw any hasty conclusions if you find your URLs are gray while competitors' are green. This is not an indicator of penalty, devaluation, or a technical issue. It simply means you (or the observed user) are part of a different test group.

Also, avoid spending time looking for a pattern (site type, sector, geography) that might explain which version you are seeing. Google segments its tests based on complex, often invisible, internal criteria that are not documented. Investing energy in deciphering these patterns is unproductive—unless you are a UX researcher passionate about it, but this is not actionable SEO.

How to monitor the evolution of these tests without wasting time?

If you are keen to monitor these variations for your watch, do so in a passive and opportunistic manner. Note the changes you observe, but do not allocate dedicated analytical resources. Google may eventually stabilize a version or continue alternating indefinitely.

However, remain attentive to changes in rich snippets, structured breadcrumbs, and other SERP elements that you can influence through Schema.org markup. These levers have a measurable impact on CTR and deserve your attention. The growing complexity of the SERPs and the increasing number of interface tests can make fine-tuning your presence in search results difficult. If you notice your CTR performances stagnating or want to maximize every available lever, consulting a specialized SEO agency can provide you with expert insight and tailored support on the truly actionable elements of your visibility.

• Do not change your SEO strategy based on the display color of URLs.
• Continue optimizing the structure of your URLs (readable, short, with keywords).
• Focus on title tags and meta descriptions to maximize CTR.
• Implement Schema.org markup to enhance your results (breadcrumbs, FAQ, reviews).
• Monitor your CTR performances in Search Console but do not attribute them to color variations.
• Stay informed of official announcements from Google regarding SERP changes, without overreacting to cosmetic details.