HTTPS and Mobile Indexing: Why Does Google Treat HTTP and HTTPS as Two Different Sites?

Why does Google separate HTTP and HTTPS in mobile indexing?

John Mueller's statement reveals a technical point often overlooked: HTTP and HTTPS are not just a simple protocol variation for Google but rather two distinct entities in its indexing system. When a site switches to mobile-first indexing for its HTTP version, Google does not automatically transfer this status to the HTTPS version.

This separation is due to how Googlebot processes URLs. Each protocol generates technically different URLs (http://example.com vs https://example.com), and the engine considers them as separate resources. Crawl, indexing, and ranking signals are thus collected and assessed independently for each version.

What are the implications for a HTTPS migration that has already been completed?

If you migrated to HTTPS several months ago, you may think everything is settled. Not true. Google may be indexing your HTTP version as mobile-first while your HTTPS version remains in desktop-first indexing, or vice versa. This discrepancy creates a situation where your mobile performance does not reflect the canonical version you wish to prioritize.

The major risk? Google continuing to primarily crawl the HTTP version, thereby diluting the quality signals sent to the HTTPS version. Your backlinks, internal link structure, and Core Web Vitals may be evaluated on the wrong version. The outcome: unexplained ranking fluctuations and loss of control over the version that truly matters.

How does Google decide which version to index with mobile-first?

Google considers several criteria for each protocol: mobile content quality, loading speed, user experience, and redirect consistency. If your HTTP version shows well-structured mobile content but your HTTPS has errors (unstable SSL certificate, blocked mixed resources, chained redirects), Googlebot may prefer HTTP for mobile indexing.

This logic explains why some sites see performance disparities between HTTP and HTTPS in Search Console. Crawl data, exploration errors, and engagement metrics are segmented by protocol. If you monitor only one version, you're missing critical signals about the other.

• HTTP and HTTPS are treated as two distinct URLs by Googlebot, with separate crawl queues and indexing signals.
• Switching to mobile-first indexing for one version does not automatically transfer to the other protocol.
• Google independently assesses mobile quality for each version, potentially creating processing disparities if one is better optimized than the other.
• 301 redirects from HTTP to HTTPS are not enough: Google must recognize HTTPS as the canonical version for all signals (backlinks, content, UX).
• An incomplete HTTPS migration may allow Google to index the HTTP version as mobile-first for months, weakening the secured version you want to prioritize.

Does this HTTP/HTTPS distinction align with real-world observations?

Absolutely. SEO audits regularly reveal sites migrated to HTTPS that still receive primary crawling on HTTP, sometimes months after migration. Search Console then shows conflicting data: the HTTP version displays a high impression volume in mobile, while HTTPS stagnates. This is not a bug, it's the direct result of this structural separation of protocols.

The issue becomes critical when backlinks still heavily point to HTTP. Google follows these links, crawls the HTTP version, and may decide to index it as mobile-first if it shows better signals than HTTPS (speed, absence of JS errors, complete mobile content). The result: your HTTPS migration effort does not translate to a ranking gain, as Google favors the older version.

What nuances should be added to Mueller's statement?

Mueller does not specify how long Google maintains this separation after a migration. In practice, if you've correctly set up your 301 redirects, submitted the HTTPS version via Search Console, and updated your sitemaps, Google eventually consolidates signals on HTTPS. However, this process can take several weeks or even months, depending on the crawl frequency and the quality of the signals sent.

Another nuance: this separation does not mean that Google completely ignores redirects. A 301 redirect from HTTP to HTTPS remains a strong signal of canonicalization. But if the HTTPS version has issues (degraded response time, truncated mobile content, intermittent SSL errors), Google may choose to continue indexing HTTP, considering it the most stable version for mobile users.

In what cases does this separation cause the most problems?

E-commerce sites and media outlets are particularly vulnerable. During an HTTPS migration, if product listings in HTTPS load slower than their HTTP counterparts (due to unoptimized external resources, poorly configured CDNs, or blocking scripts), Google may maintain mobile indexing on HTTP. You then lose the benefit of HTTPS ranking boost, and mobile conversions drop.

Another problematic case: sites with multiple subdomains. If you migrate www.example.com to HTTPS but forget blog.example.com or shop.example.com, Google treats each subdomain independently. The result: certain sections of your site remain in HTTP for mobile indexing, creating a fragmented user experience and diluted quality signal. [To be verified]: Google does not provide precise metrics on the average consolidation time post-migration, complicating impact estimation.

What should you check immediately after an HTTPS migration?

The first urgency: Search Console. Add the four variants of your site (http://www, https://www, http://, https://) as distinct properties. Compare crawl volumes, impressions, and errors between HTTP and HTTPS. If HTTP continues to receive more than 20% of mobile crawl one month after migration, you have a signal consolidation issue.

The second action: audit your 301 redirects. Each HTTP URL should point directly to its HTTPS equivalent, without a chain of redirects. Routing through an intermediate domain (example: http://example.com → http://www.example.com → https://www.example.com) dilutes PageRank and slows consolidation. Manually test a dozen strategic URLs (homepage, main categories, best-sellers) to confirm that the redirect is unique and fast.

How can you speed up the transfer of mobile indexing to HTTPS?

Submit a HTTPS-only XML sitemap via Search Console, removing any residual HTTP sitemaps. Google uses sitemaps as a signal of preference: if you still submit HTTP URLs, it continues to crawl them. Also, ensure that your robots.txt does not block Googlebot on HTTPS while allowing HTTP (a common error during poorly coordinated migrations).

Update your strongest backlinks. Contact the sites that send you the most juice (quality directories, partners, media) to correct their links to HTTPS. Each direct backlink to HTTPS strengthens the canonical signal and speeds up the transfer of authority. Meanwhile, monitor your internal links: a single template that still points to HTTP (menu, footer, breadcrumb) can generate thousands of stray links.

What mistakes to avoid to prevent signal fragmentation?

Do not allow HTTP and HTTPS to coexist without strict redirection. Some sites keep HTTP accessible "just in case", thinking this avoids 404 errors. Fatal mistake: Google then crawls both versions, dilutes ranking signals, and may even consider HTTP as the canonical version if it loads faster. Block HTTP at the server level or enforce an immediate 301 redirect without exception.

Avoid unstable or self-signed SSL certificates. If Google detects SSL errors during an HTTPS crawl (expired certificate, incomplete certification chain, blocking mixed content), it may switch to HTTP to ensure stable indexing. Use a recognized certificate (Let's Encrypt is more than sufficient) and regularly test its validity using tools like SSL Labs.

• Add the four variants of the site (http://, https://, http://www, https://www) in Search Console and compare mobile crawl volumes.
• Ensure that each HTTP URL redirects directly to HTTPS with a 301, without intermediate redirect chains.
• Submit only a HTTPS sitemap and delete any residual HTTP sitemap from Search Console.
• Audit key backlinks and request corrections for links still pointing to HTTP.
• Force HTTPS at the server level (HSTS) to eliminate any possibility of HTTP access without redirection.
• Test the validity of the SSL certificate and immediately correct any mixed content (HTTP resources on HTTPS pages).