Search crawlers and screen readers are, in a real sense, the same kind of user. Both arrive without a mouse, without color perception, and without the ability to guess what an unlabeled button does. Both parse your page as a structured document, not a picture. That shared dependency on clean, semantic markup is why accessibility and SEO keep producing the same to-do list from two different audits.
This isn't a tidy story where every accessibility fix ranks you higher — most WCAG success criteria have no direct ranking effect, and you should build for people first regardless. But the overlap is large and concrete. Below are the five places where one change earns two wins, with the technical detail that separates a real fix from a checkbox.
Semantic headings: one outline for screen readers and crawlers
Many screen reader users navigate by pulling up a list of headings and jumping between them — headings are one of the most common ways people find information on a page. A search crawler builds a near-identical model: it reads your h1 through h6 to understand topic hierarchy and which passages answer which query. When your headings are real heading elements in a logical order, both audiences get a usable table of contents for free.
The failure mode is the same on both sides: a <div class="title"> styled to look like a heading is invisible to the heading list and carries no structural weight for search. So is skipping from h2 to h4 because h3 looked too big — that breaks the WCAG 1.3.1 Info and Relationships expectation and muddies the outline. Use exactly one h1 that matches the page's primary intent, nest levels without gaps, and never pick a tag for its font size (that's what CSS is for).
- Do:
<h2>for each major section,<h3>for sub-points within it, in source order. - Don't: bold paragraph text standing in for a heading, or heading tags chosen by visual weight.
- Check both: our heading structure checker flags skipped levels and multiple
h1s in seconds.
Marketers often discover their on-page SEO heading hierarchy and their accessibility heading audit are literally the same fix list. Resolve it once and both reports go green.
Alt text: the same description serves image search and screen readers
The alt attribute is the rare element that search engines and assistive technology consume verbatim. A screen reader announces it in place of the image; Google Images uses it (alongside filename and surrounding text) to understand and rank the picture. Write one good description and you've fed both.
Good means specific and contextual, not keyword soup. alt="Barista pouring a rosetta into a flat white" beats alt="coffee coffee shop best coffee near me" for a person hearing it read aloud and for a crawler trying to match intent — keyword stuffing in alt text can read as spam and helps no one. Two technical rules people miss: decorative images that add no information should carry an empty alt="" so screen readers skip them, and an image that is itself a link must describe the link's destination, not the picture. Run pages through the alt text checker to catch missing and empty attributes at scale.
Link text: "click here" fails screen readers and link signals alike
Screen reader users frequently navigate by pulling up a list of every link on the page, stripped of surrounding sentences. A page full of "click here," "read more," and "learn more" becomes a list of identical, meaningless entries — a direct WCAG 2.4.4 Link Purpose failure. Search engines lean on that same anchor text to understand what the linked page is about; it's one of the oldest relevance signals there is.
Descriptive anchor text fixes both at once. An anchor like "our accessibility audit checklist" tells a screen reader user exactly where they'll land and tells a crawler the target page is about audits. The rule of thumb: each link should make sense read entirely on its own. As a bonus, descriptive anchors distribute topical context across your site the way both crawlers and out-of-context navigation expect.
Captions and transcripts: making audio and video machine-readable
Crawlers cannot watch a video or listen to a podcast. Neither can a Deaf or hard-of-hearing visitor. The single artifact that solves both — a caption track and a text transcript — turns minutes of otherwise opaque media into indexable, searchable, quotable text.
WCAG requires captions for prerecorded video (1.2.2) and adds further requirements for audio description and transcripts across the 1.2.x criteria. Practically: ship a real .vtt caption file rather than relying on auto-captions alone (auto-captions routinely mangle names and jargon, which hurts comprehension and indexing equally), and publish the full transcript as on-page text below the player. That transcript is genuine indexable content — it can rank for long-tail phrases the video covers and gives you internal-linking surface area you didn't have before.
Performance and stable layout: Core Web Vitals are accessibility wins too
Page experience is where the overlap gets measurable. Core Web Vitals are a confirmed (if modest) ranking input, and two of the three are also accessibility concerns. Cumulative Layout Shift — content jumping as images and ads load — is a genuine barrier for users with motor or cognitive disabilities who tap a target that moves; setting explicit width/height or aspect-ratio on media fixes the shift for everyone. Interaction to Next Paint rewards responsive, non-blocking interfaces, which is exactly what keyboard and switch-device users need.
Adjacent WCAG criteria reinforce this. 1.4.10 Reflow (AA) requires content to work at 320 CSS pixels wide without horizontal scrolling — the same responsive discipline that helps mobile rankings. 1.4.4 Resize Text (AA) requires usability at 200% zoom. 2.5.8 Target Size (Minimum, AA) in WCAG 2.2 asks for interactive targets of at least 24×24 CSS pixels, which also reduces mis-taps. Build to these and you're simultaneously satisfying the page-experience signals search engines reward and the layout rules assistive-tech users depend on.
It's worth being precise about scope: this overlap is the easy part, not the whole job. Color contrast (4.5:1 for normal text, 3:1 for large text and UI components), visible focus indicators (2.4.7), keyboard operability, and accessible forms carry little to no SEO weight — you do them because they're required by WCAG 2.2 Level A and AA and by laws like the EU's European Accessibility Act, which has applied since 28 June 2025 with WCAG 2.2 A/AA as its baseline via EN 301 549. Treat SEO overlap as the incentive that gets the project funded, then finish the parts that only help humans.
Where to start
Run a single scan that surfaces the shared issues first — missing alt text, broken heading order, vague links, contrast and structural problems — then triage. The overlapping items pay for themselves twice, so they're the natural first sprint.
- Scan it: check any page free with AccessScan to see headings, alt text, contrast, and link issues in one report.
- Go deeper: work through the accessibility checklist to cover the human-only criteria SEO won't flag.
- Document it: generate an accessibility statement once you've made measurable progress.
Build for people who navigate by structure rather than sight, and you'll have built for the crawlers too. The reverse — chasing rankings with hollow markup — helps neither. Same outline, two audiences, one set of fixes.