SEO Accessibility: What Most Sites Get Wrong

SEO accessibility means making your website technically and structurally legible to both search engines and every human who lands on it, regardless of how they browse. When those two goals align, rankings tend to improve. When they conflict, something has usually gone wrong in how the site was built or how the SEO brief was written.

Most accessibility problems are not exotic edge cases. They are systematic failures that compound quietly over time, depressing crawl efficiency, reducing engagement signals, and locking out segments of your audience without anyone noticing until the traffic data tells a different story.

Why Accessibility and SEO Are the Same Problem

There is a version of this conversation that treats accessibility as a legal obligation and SEO as a commercial one, and keeps them in separate workstreams. That framing is operationally convenient and strategically wrong.

Googlebot does not render the web the way a sighted user with a fast connection and a modern browser does. It reads structure. It follows hierarchy. It depends on text alternatives for non-text content. It struggles with the same things a screen reader struggles with: missing labels, broken heading sequences, JavaScript-dependent content that never resolves, and interactive elements that have no accessible name.

When I was running agency teams across multiple verticals, one of the more instructive exercises we ran was a crawl-versus-render comparison for a large e-commerce client. The site looked fine in a browser. The crawl data told a different story: thousands of product pages where the primary descriptive content lived inside a JavaScript component that Googlebot was either not rendering or rendering inconsistently. The SEO team had been optimising page titles and meta descriptions for months. The content those tags were supposed to represent was effectively invisible to the crawler. Fixing the rendering issue moved rankings more in eight weeks than the previous six months of on-page work had.

That is not a unique story. It is a pattern. And the root cause is almost always the same: the people building the site were not thinking about how machines read it, only about how humans see it.

If you are working through a broader SEO framework, the Complete SEO Strategy hub covers the full picture, from technical foundations through to content and authority signals.

What “Accessible” Actually Means in an SEO Context

Accessibility standards are codified in the Web Content Accessibility Guidelines, commonly referred to as WCAG. The current standard is WCAG 2.2, with 2.1 still widely referenced. The guidelines are organised around four principles: perceivable, operable, understandable, and strong. Every principle has a direct SEO analogue.

Perceivable means that content can be perceived regardless of the user’s sensory abilities. For SEO, this maps directly to whether content is readable by a crawler: text alternatives for images, captions for video, and content that does not depend on colour alone to convey meaning.

Operable means that the interface can be used without a mouse. For SEO, this connects to crawlability: can a crawler follow your navigation? Are links keyboard-accessible? Is the site structure logical enough that a non-visual agent can move through it predictably?

Understandable means that content and interface behaviour are predictable. For SEO, this connects to user signals: if people cannot understand what a page is about or how to use it, they leave quickly. Dwell time drops. Engagement signals weaken. Rankings follow.

strong means that content can be reliably interpreted by current and future user agents. For SEO, this is the technical foundation: clean HTML, valid markup, content that does not depend on deprecated technologies or fragile rendering conditions.

None of these are niche concerns. They are the same things a competent technical SEO audit covers. The overlap is not coincidental.

The Three Areas Where Sites Consistently Fail

After auditing sites across retail, financial services, professional services, and media, the same failure modes appear with remarkable consistency. They are not complicated. They are just neglected.

Image Alt Text

Missing or poorly written alt text is the single most common accessibility failure I encounter on commercial sites. It is also one of the most direct SEO costs, because images without descriptive alt text are invisible to crawlers in any meaningful sense. Google can use surrounding context to make inferences, but it is doing interpretive work that you should be doing for it.

The failure usually happens at the content management level. Writers upload images without filling in the alt field. Developers set default alt attributes to empty strings. E-commerce platforms auto-generate alt text from file names, which produces descriptions like “IMG_4872.jpg” at scale.

Good alt text describes what the image shows in plain language, includes a relevant keyword where it fits naturally, and does not start with “image of” or “photo of.” It is written for someone who cannot see the image, which is exactly the right frame for writing it for a crawler.

Decorative images should have empty alt attributes, not missing ones. The distinction matters: an empty alt attribute tells assistive technology to skip the image. A missing one leaves the behaviour undefined, which creates noise in both accessibility audits and crawl reports.

Heading Hierarchy

Heading structure is how both crawlers and screen readers understand the organisation of a page. A logical heading hierarchy, H1 followed by H2s, with H3s nested under the relevant H2, creates a document outline that communicates content structure without requiring visual rendering.

Most sites have heading hierarchy problems. The most common is using heading tags for visual styling rather than semantic meaning: an H3 chosen because the font size looks right, not because it represents a subsection of the preceding H2. The result is a heading structure that makes no logical sense when read linearly, which is exactly how a crawler reads it.

A related problem is multiple H1s. One H1 per page is the correct approach. When CMS templates generate H1s automatically and content editors add their own, you end up with pages that have two or three competing primary headings. The signal is diluted and the structure is ambiguous.

Skipped heading levels are also common: jumping from H2 directly to H4, or from H1 to H3. These are not catastrophic failures, but they indicate a site where semantic structure was not part of the build brief, which usually means other structural problems are present too.

Keyboard Navigation and Link Clarity

Keyboard navigation matters for accessibility because not every user can operate a mouse. It matters for SEO because crawlers follow links, and links that are only accessible via mouse interaction, hover states, JavaScript-triggered menus that do not degrade gracefully, are links that crawlers may not follow.

Anchor text quality is a related issue. Links labelled “click here” or “read more” are problematic for screen reader users who handle by link lists, and they are weak SEO signals because they tell the crawler nothing about the destination page. Descriptive anchor text, the kind that makes sense out of context, serves both audiences simultaneously.

Focus indicators are another consistent failure. When a user navigates by keyboard, the focused element should be visually highlighted so they know where they are on the page. Many sites suppress focus indicators for aesthetic reasons, which creates a navigation experience that is unusable for keyboard-dependent users and breaks the logical flow that crawlers expect.

Core Web Vitals, Page Experience, and the Accessibility Connection

Google’s Core Web Vitals are a set of performance metrics that measure loading speed, interactivity, and visual stability. They became a ranking signal in 2021. The connection to accessibility is more direct than most teams recognise.

Cumulative Layout Shift, the visual stability metric, measures how much page elements move unexpectedly during loading. High CLS scores are disorienting for all users, but they are particularly problematic for users with cognitive disabilities, and for users on assistive technology where unexpected movement can cause loss of context. Fixing CLS, by specifying image dimensions, reserving space for dynamic content, and avoiding late-loading elements that push content down, improves both the Core Web Vitals score and the accessibility of the page.

Interaction to Next Paint, which replaced First Input Delay as the interactivity metric, measures how quickly a page responds to user input. Pages that are slow to respond are frustrating for all users, but they create particular barriers for users with motor impairments who may require more time to interact and cannot afford to repeat interactions that did not register. Performance optimisation and accessibility optimisation are pointing in the same direction.

I have seen teams treat Core Web Vitals as a developer problem and accessibility as a compliance problem, with neither workstream talking to the other. The result is duplicated effort, missed synergies, and sites that pass neither standard as efficiently as they could. Running them as a single workstream, with shared success metrics, is more effective and more honest about what is actually being measured.

Structured Data and Semantic HTML as Accessibility Infrastructure

Structured data markup, schema.org vocabulary implemented in JSON-LD, is how you communicate explicitly to search engines what your content is about, who created it, what type of entity it describes, and how it relates to other content. It is an SEO tool. It is also an accessibility tool, because it contributes to the semantic layer that makes content machine-readable in a consistent, predictable way.

The same logic applies to semantic HTML more broadly. Using the correct HTML elements for their intended purpose, nav for navigation, main for main content, article for article content, aside for supplementary content, gives assistive technology reliable landmarks to work with. Screen reader users can jump directly to the main content, skip navigation, or move between sections without reading every element on the page. Crawlers benefit from the same structural clarity.

When I judged the Effie Awards, one of the things that stood out in the submissions that held up under scrutiny was a clarity of purpose that ran from the brief through to the execution. The best-performing campaigns were not complicated. They were clear. The same principle applies to site architecture: clarity of structure, communicated through the right semantic elements, is what makes a site legible to every agent that needs to read it.

ARIA attributes, Accessible Rich Internet Applications, are a supplementary layer for cases where native HTML semantics are insufficient, typically in complex interactive components. They should be used to augment semantics, not replace them. The common mistake is using ARIA to compensate for non-semantic markup: adding role=”button” to a div instead of using an actual button element. This creates brittle accessibility that breaks under edge conditions and adds complexity without adding robustness.

Content Accessibility Beyond Technical Compliance

Technical accessibility is necessary but not sufficient. Content accessibility, the readability, clarity, and structural logic of the writing itself, is where many sites that pass technical audits still fail their audiences.

Plain language is an accessibility standard. It is also an SEO standard, because content that is difficult to read produces weaker engagement signals and is harder for crawlers to parse for topical relevance. Sentences that are too long, vocabulary that assumes specialist knowledge, and paragraphs that bury the main point in the third sentence are problems for users with cognitive disabilities, for users reading in a second language, and for users who are simply busy and scanning rather than reading linearly.

The tools available for understanding how users actually interact with content have improved significantly. Session replay tools show you where users stop scrolling, where they click in frustration, and where they abandon pages that should be holding their attention. That behavioural data is worth more than most readability scores, because it shows you the real cost of content that is not accessible in the practical sense, not just the technical one. If you want to move beyond assumptions about how users read your content, reducing those assumptions with behavioural data is the right starting point.

Captions and transcripts for video content are another area where technical and content accessibility converge with SEO. Video content without a transcript is largely opaque to crawlers. Adding a transcript makes the content indexable, improves accessibility for deaf and hard-of-hearing users, and creates a text asset that can support the page’s topical relevance. It is one of the higher-return accessibility investments available to content teams.

How to Audit for Accessibility Issues That Affect SEO

A useful accessibility audit for SEO purposes does not require specialist tools, though they help. It requires a systematic approach to the failure modes most likely to affect crawlability, indexability, and user signals.

Start with automated tools. Lighthouse, built into Chrome DevTools, runs an accessibility audit alongside performance and SEO checks and gives you a prioritised list of issues with specific element references. axe DevTools, available as a browser extension, is more thorough for accessibility-specific issues. Screaming Frog, if you are using it for SEO crawls, can be configured to flag missing alt text, heading structure problems, and broken links simultaneously.

Automated tools catch roughly 30 to 40 percent of accessibility issues. The rest require manual testing. The most efficient manual tests for SEO-relevant accessibility are: keyboard-only navigation through the site’s primary user journeys, a heading structure review using a browser extension that extracts the heading outline, and a check of all interactive elements for accessible names using the browser’s accessibility tree.

Prioritise by traffic and commercial value. An accessibility failure on your homepage or your highest-traffic landing pages costs more than the same failure on a low-traffic support page. Fix in order of impact, not in order of discovery.

One thing I have found useful when presenting accessibility findings to commercial stakeholders is framing issues in terms of the audience they exclude and the revenue implication of that exclusion, rather than the compliance risk. Compliance risk is real, but it is abstract. “This checkout flow is not usable by keyboard-only users, and keyboard-only users represent a measurable percentage of your customer base” is a more actionable framing for a business that is focused on growth rather than risk management.

The lessons from failed SEO tests are often more instructive than the successes, and accessibility is no exception. Sites that have run accessibility improvements as controlled tests and measured the SEO impact have produced some of the clearest evidence that these two disciplines are not separate concerns.

Building Accessibility Into the Content Production Process

Retrofitting accessibility onto a large site is expensive and slow. Building it into the production process is cheaper, faster, and more durable. The question is where in the process to intervene.

For content teams, the intervention points are: the brief (does it specify heading structure, alt text requirements, and reading level targets?), the editorial review (does the review process check for structural and language accessibility, not just factual accuracy?), and the publishing workflow (does the CMS enforce or encourage accessible markup, or does it make it easy to skip?).

For development teams, the intervention points are: the component library (are components built with accessible semantics as a default, not an afterthought?), the design system (does it specify focus states, colour contrast ratios, and touch target sizes?), and the QA process (does QA include accessibility testing, or only functional testing?).

When I grew an agency from 20 to 100 people, one of the things that broke early and had to be rebuilt was the quality assurance process. At 20 people, quality was maintained by proximity: everyone knew what the standards were because they had been set by the same small group. At 100 people, standards had to be documented, embedded in process, and checked systematically. Accessibility standards work the same way. They do not survive growth without process infrastructure.

The Content Marketing Institute’s how-to resources cover content process in depth, and the principle that applies here is that quality at scale requires systems, not just intention. Accessibility is a quality standard. It needs the same process infrastructure as any other quality standard.

Training matters too, but it has to be specific. Generic “accessibility awareness” training produces awareness without behaviour change. Training that shows a content writer exactly how to write alt text, exactly how to structure headings in the CMS they use every day, and exactly what the SEO impact of getting it wrong looks like, produces behaviour change. The specificity is the point.

The E-E-A-T Dimension of Accessibility

Google’s E-E-A-T framework, Experience, Expertise, Authoritativeness, and Trustworthiness, is a quality signal framework rather than a direct ranking algorithm. But it shapes how quality raters assess pages, and those assessments influence how the algorithm is calibrated over time.

Accessibility connects to E-E-A-T in ways that are not always obvious. A site that is structurally inaccessible signals, at some level, that it was not built with care. Broken heading structures, missing alt text, and unnavigable interactive elements are not the marks of a site that takes its content or its audience seriously. Quality raters are assessing the overall experience of using a site, not just the factual accuracy of its content.

Trustworthiness, the T in E-E-A-T, is the dimension most directly affected. A site that excludes users through poor accessibility is not demonstrating trustworthiness in any meaningful sense. It is demonstrating that the people who built it were not thinking about the full range of people who would use it. That is a content quality signal, even if it is not coded as one in any explicit way.

The SEO community sometimes treats E-E-A-T as a content marketing problem, something to be addressed through author bios and citation strategies. It is also a technical and structural problem, addressed through the same work that makes a site accessible. The two are not in competition. They are pointing at the same underlying standard: build something that works properly for the people who need to use it.

If you are building out your SEO programme and want to see how accessibility fits into the broader picture, the Complete SEO Strategy hub pulls together the technical, content, and authority dimensions in one place.

About the Author

Keith Lacy is a marketing strategist and former agency CEO with 20+ years of experience across agency leadership, performance marketing, and commercial strategy. He writes The Marketing Juice to cut through the noise and share what works.

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