Structure check

How it works

1. Open the page you want to check in your browser. Right-click on the page and choose ‘View page source’. In Edge, Chrome and Firefox you can also press Ctrl+U. On a Mac that is Cmd+Option+U.
2. Copy everything (Ctrl+A and then Ctrl+C) and paste it into the box.
3. Press ‘Check the HTML’.
4. Read the result. For each part you see what is missing, where it is, why it matters and how to fix it. You see the headings as an indented list, like a table of contents.
5. Change your page and check again. Want to keep the result or pass it on? Choose Print above the tool.

No page to hand? Choose ‘Try an example’. Then you see what the check does with a made-up page.

What the check looks at

• Language, title and main content. Does the page say its language, does it have a title and is there a main element? The check only looks at this if you paste a whole page.
• Headings. You see the headings as a list. The check reports a skipped level, a page without an h1 or with more than one h1, and headings without text.
• Images without alt text, or with an alt text that says little, such as a file name.
• Links without text, or with a vague text like ‘click here’ or ‘read more’.
• Buttons without a name, such as a button with only an icon.
• Form fields without a label, or with only placeholder text in the field.

Each issue shows its number from WCAG. That is the international guideline for accessible websites. Want to know more? Read what is WCAG.

How serious is an issue?

Each issue has a label in words:

• Does not meet WCAG: this needs to change.
• Check yourself: it depends on where it is. ‘Read more’ can be fine if the sentence around it says where the link goes. The check can’t judge that.
• Good practice: not a strict WCAG requirement, but something W3C recommends. For example, not skipping a heading level.

A quick check, not a full audit

The check only reads the HTML. It doesn’t see what the page looks like, what CSS and JavaScript do, whether you can use the page with the keyboard or whether the colours have enough contrast. It does see whether there is an alt text, but not whether it matches the image.

Does the check find nothing? Then your page is not necessarily accessible. For a full audit, go through all the WCAG requirements (the success criteria), or have an expert do it.

Test further:

• Keyboard test: does your website work with just the keyboard?
• Colour-blind view: can your text be read easily against the background?
• Alt text helper: what do you write in the alt text of an image?
• Making your website accessible: where do you start?
• Accessible website checklist: everything in one place.

Check it yourself

Is the check not working, or would you rather do it by hand? You can also do it like this:

1. Open the page source (right-click, ‘View page source’). Use Ctrl+F to search for the bits below.
2. Search for <html: does it have a language, such as lang="en"? Search for <title: does the title say what the page is about? Search for <main: is there one?
3. Search for <h1, <h2 and so on. Write the headings down on paper, one below the other, with the level in front. Is there one h1? Does the level only ever go down one step at a time?
4. Search for <img: does every image have an alt?
5. Search for <a , <button and <input. Does the text of each link say where it goes? Does each button say what it does? Does each form field have a label?

Your HTML

The HTML stays on your own device. The check happens in your browser and reads the HTML as text. Scripts in the HTML don’t run, and images and other files are not loaded. We don’t send anything and we don’t store anything. If you close the page, the HTML is gone.

Note: a browser extension that reads along, such as a writing assistant, can see what you paste. That is outside this page. Are you checking a page you are logged in to? Then the HTML may contain data about you or your clients. In that case, check the public version instead.

Sources

The explanation for each issue follows WCAG 2.2 and the W3C explanations. Read on 30 September 2026.

• WCAG 2.2, Dutch translation (external website)
• Headings (W3C WAI, Page Structure Tutorial) (external website)
• Decorative Images (W3C WAI, Images Tutorial) (external website)
• Understanding Success Criterion 2.4.4: Link Purpose (In Context) (external website)
• Labeling Controls (W3C WAI, Forms Tutorial) (external website)
• Form Instructions (W3C WAI, Forms Tutorial) (external website)