A website can look completely fine and still have problems hiding underneath. The homepage loads, the navigation works, and nothing obviously seems broken, but that doesn't tell you whether search engines can properly understand the site, whether important technical information is missing, or whether performance problems are quietly affecting users.
So we decided to test it. We ran 100 websites through HeronSignal's Scan to see what a normal website looks like when you inspect more than what appears in the browser.
Here's what we found.
How We Ran the Test
We selected 100 publicly accessible websites and ran each one through HeronSignal's Scan. The scanner checks different parts of a website, including SEO, performance, AI readiness, structured data, sitemap and robots.txt configuration, security, SSL, and other technical issues.
The idea wasn't to find deliberately bad websites. We wanted a mix of real websites that people are actively using and maintaining, then see what problems were hiding underneath them.
Most Websites Weren't Actually Broken
The first thing we noticed was that most of the websites worked perfectly well from a visitor's perspective. You could open them, navigate between pages, click buttons, and probably leave without thinking anything was wrong.
The scans told a different story. Across the websites we tested, we found missing metadata, structured data problems, performance warnings, sitemap and robots.txt issues, broken links, and other configuration problems.
These aren't necessarily the kind of issues that make a website completely unusable. That's exactly why they're easy to miss. A website can continue working for months while smaller technical problems accumulate underneath it.
Technical SEO Problems Are Easy to Miss
SEO is often treated as a content problem: keywords, articles, backlinks, and rankings. But there is another layer underneath all of that.
The Scan checks things like page titles, meta descriptions, canonical URLs, sitemaps, robots.txt, structured data, and whether pages are configured in a way that makes sense to search engines. We found issues in these areas even on websites that looked completely normal from the outside.
That's what makes technical SEO problems particularly easy to overlook. A missing canonical tag or incorrectly configured sitemap doesn't necessarily change what a visitor sees, but it can change how a crawler understands the website.
Performance Is Hard to Judge by Opening the Website Yourself
Another common mistake is testing website performance by simply opening the site and seeing whether it feels fast.
That experience depends on your connection, device, location, browser cache, and several other factors. A homepage can also perform well while another important page has completely different problems.
The performance checks gave us a more useful view because they exposed issues that weren't necessarily obvious during normal browsing. Instead of relying on whether a page "feels fast," you can look at what is actually happening and which parts of the site need attention.
AI Readiness Is Still Inconsistent
We also looked at how websites are prepared for AI systems. This is still a developing area, and the scans showed how inconsistent the web currently is.
HeronSignal checks signals such as llms.txt, structured data, page structure, and other machine-readable information. None of these checks individually determines whether an AI system can understand or discover a website, but together they give us an interesting picture of how much thought has gone into making a site's information accessible beyond traditional human visitors.
This matters because websites are increasingly being consumed by more than browsers and search engines. AI assistants, agents, and other automated systems are becoming another way people discover and interact with information on the web.
The Bigger Problem Wasn't Any Individual Issue
After going through the scans, the most interesting finding wasn't one particular SEO problem or performance warning. It was how easily all of these problems can exist without anyone noticing.
Most teams know whether their website is online. They don't necessarily know whether an important page has become slower, structured data has broken, a sitemap is incorrectly configured, or something changed during the latest deployment.
Usually, somebody notices when the problem becomes large enough to have an obvious effect. A customer complains, traffic drops, a page stops appearing where expected, or a developer happens to discover an error.
That means the problem may have already existed for days or weeks before anyone starts investigating it.
A Scan Is a Snapshot
This is also an important limitation of any website scanner. A scan tells you what is happening at a particular point in time.
A website can score well today and have a problem tomorrow. A new deployment can introduce an error, an external API can fail, a payment provider can have problems, or a seemingly harmless code change can affect performance.
That's why we treat the Scan as an entry point rather than the entire monitoring process. It helps you understand the current state of a website without installing anything, while continuous monitoring answers the harder question: what changed after you checked?
From Finding a Problem to Actually Fixing It
Finding problems is useful, but it isn't where we want HeronSignal to stop.
The broader workflow we're building is simple: detect an issue, understand what it affects, help fix it, and then continue watching production to verify that the problem actually went away.
That last part matters. A merged pull request doesn't necessarily mean a production issue has been solved. The real confirmation comes from seeing the original error disappear or the affected metric recover after the fix is deployed.
The Scan is the simplest way to experience the first part of that workflow. You enter a website, wait a couple of minutes, and get a report showing what HeronSignal can see without installing an SDK or creating an account.
What We Learned
Scanning 100 websites changed the question for us. Instead of asking whether a website is working, it makes more sense to ask whether anyone actually knows how healthy it is.
Most of the websites we tested weren't catastrophically broken. They had smaller issues that were easy to overlook because everything still appeared to work. That's probably the more realistic state of the web: not thousands of completely broken websites, but millions of working websites with problems nobody has noticed yet.
That's the reason we built the HeronSignal Scan. It gives you a quick way to look underneath your website and see what might be worth paying attention to before one of those small problems becomes a much bigger one.
See What HeronSignal Finds on Your Website
You don't need to install anything or create an account to run your first scan. Enter your website URL and HeronSignal will analyze it across performance, SEO, security, AI readiness, and other technical checks, then show you what needs attention.
Run a free HeronSignal Scan and see what your website looks like underneath the surface.
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