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Accessibility checking

Rocket Validator looks for accesibility violations on your pages using the axe-core accessibility engine, hosted on our own servers and integrated into our web crawler. You don't need to buy an additional license, everything's already included in your Pro account at Rocket Validator.

List of accessibility rules checked

These are the 74 rules that will be checked on every page of your sites. Click on each to get an extended description.

accesskey attribute value must be unique.
All accesskey attribute values in a document must be unique. Put another way, accesskeys must not be repeated to prevent unexpected effects for keyboard users.
Active area elements must have alternate text.
An image map is a single image with many clickable areas. Like all images, an image map must have alternate text for each of the different clickable areas, as well as for the larger image itself, since screen readers have no way of translating graphics into text.
All cells in a table element that use the headers attribute must only refer to other cells of that same table.
Data table markup can be tedious and confusing. Markup tables semantically and with the correct header structure. Screen readers have features to ease table navigation, but tables must be marked up accurately for these features to work correctly.
All non-empty td element in table larger than 3 by 3 must have an associated table header.
Data table markup can be tedious and confusing. Tables must be marked up done semantically and with the correct header structure. Screen readers have features to ease table navigation, but tables must be marked up accurately for these features to work correctly.
All page content must be contained by landmarks.
It is best practice to contain all content, with the exception of skip links, within distinct regions such as the header (role='banner'), content (role='main'), and footer (role='contentinfo').
All th elements and elements with role='columnheader' or role='rowheader' must have data cells they describe.
Data table markup can be tedious and confusing. Markup tables semantically and with the correct header structure. Screen readers have features to ease table navigation, but tables must be marked up accurately for these features to work correctly.
Anchors must only be used as links with valid URLs or URL fragments.
Anchor links must be used with valid URLs or URL fragments so that they are discernible by a screen reader.
ARIA attributes must conform to valid names.
ARIA attributes (i.e. starting with aria-) must have valid names. Referring to a misspelled attribute or to one that does not exist will result in an invalid attribute and thus failure of this Rule.
ARIA attributes must conform to valid values.
ARIA attributes (i.e. starting with aria-) must contain valid values. These values must be spelled correctly and correspond to values that make sense for a particular attribute in order to perform the intended accessibility function.
ARIA role must be appropriate for the element.
Values assigned to WAI-ARIA role attributes must be valid. This means values must be spelled correctly, correspond to existing ARIA role values, and must not be abstract roles in order to correctly expose the purpose of the element.
ARIA roles used must conform to valid values.
Values assigned to ARIA role values must be valid. Role values must be spelled correctly, correspond to existing ARIA role values, and must not be abstract roles to correctly expose the purpose of the element.
aria-hidden='true' must not be present on the document body.
Document content is not accessible to assistive technology if body aria-hidden='true'.
audio elements must have a captions track.
The track element must be present for each HTML5 audio element, with kind='captions' set as a property. Captions are text—synchronized with the audio file—of the dialog, narration, and any important auditory information, for the benefit of deaf users.
Autocomplete attribute must be used correctly.
The purpose for each common input field that collects an individual's personal data is programmatically defined based on the list of 53 Input Purposes for User Interface Components. The autocomplete attribute values must be valid and correctly applied for screen readers to function correctly.
Banner landmark must not be contained in another landmark.
Banner landmark must not be contained in another landmark.
blink elements are deprecated and must not be used.
This rule requires that no blink elements are present. Flashing text can be difficult to read and blinking objects can be difficult to activate. The associated automated check finds the presence of all blink elements so that they can be removed.
Bold, italic text and font-size are not used to style p elements as a heading.
Styled p elements must not be used to represent headings because the structure of the document cannot otherwise be determined by screen reader users.
Buttons must have discernible text.
Buttons must have discernible text that clearly describes the destination, purpose, function, or action for screen reader users.
Certain ARIA roles must be contained by particular parent elements.
Certain ARIA roles must be contained by particular parent roles in order to perform the intended accessibility functions.
Certain ARIA roles must contain particular children.
Some ARIA parent role values applied to elements must contain specific child elements and role values to perform intended accessibility function.
Checkbox inputs with the same name attribute value must be part of a group.
All checkbox groups must have either a proper aria-labelledby value for all group members, or a proper containing fieldset or ARIA group to associate them programmatically for screen reader users.
Contentinfo landmark must not be contained in another landmark.
Contentinfo landmark must be at top level.
CSS Media queries are not used to lock display orientation.
The screen orientation (e.g. portrait or landscape) of mobile applications should not be locked in one mode. Users should be able to change the orientation of their device between portrait and landscape with the page adjusting accordingly in order to remain understandable. Also, when opening a page, it should display in the user’s current orientation.
Data or header cells should not be used to give caption to a data table.
Data table markup can be tedious and confusing. Screen readers have some features to ease table navigation, but tables must be marked up accurately for these features to work correctly. Some tables use cells with a colspan element to visually indicate a caption, instead of using an actual caption element.
dl elements must only directly contain properly-ordered dt and dd groups, script, or template elements.
Definition lists (dl) must contain only properly-ordered dt and dd groups, script or template elements.
Documents must contain a title element to aid in navigation.
The HTML document must have a title element to provide users with an overview of its content, and when present, it must not be empty.
dt and dd elements must be contained by a dl.
Definition list items (dt and/or dd) must be wrapped in parent dl elements to be valid. This enables screen reader users to understand the proper hierarchy of information in the list.
Elements in the focus order need a role appropriate for interactive content.
User input elements must have appropriate roles, whether native HTML or a custom widget, to convey to screen reader users their meaning when landed on and given focus. If a custom widget, appropriate ARIA role values must be used instead of abstract roles to correctly expose the purpose of the element.
Elements must only use allowed ARIA attributes.
Not all ARIA role-attribute combinations are valid. This Rule checks that each role is supplied with allowed attributes.
Elements should not have tabindex greater than zero.
A tabindex attribute must never have a value greater than 0 to prevent an unexpected tab order that can give the appearance of skipping some elements entirely.
Form elements must have labels.
Each form element must have a programmatically associated label element.
Form elements should have a visible label.
Each form element must have a programmatically associated label element.
Frames must be tested with axe-core.
Frames must be tested with axe-core.
Frames must have a unique title attribute.
All frame or iframe elements in the document must have a unique title to describe their contents to screen reader users.
Frames must have title attribute.
All frame or iframe elements in the document must have a title that is not empty to describe their contents to screen reader users.
Heading levels should only increase by one.
Headings must be in a valid logical order, meaning h1 through h6 element tags must appear in a sequentially-descending order.
Headings must not be empty.
When at least one heading element (marked by h1 through h6) is present, it is a best practice to ensure it contains content.
Hidden content on the page cannot be analyzed.
Informs users about hidden content that cannot be analyzed for accessibility violations
HTML element must have a lang attribute.
The HTML document element must contain a valid lang attribute or must correspond to a valid lang code for multilingual screen reader users who may prefer a language other than the default.
HTML element must have a valid value for the lang attribute.
The HTML document must contain a valid lang attribute or must correspond to a valid lang code for multilingual screen reader users who may prefer a language other than the default.
HTML elements with lang and xml:lang must have the same base language.
The HTML document must contain a valid lang attribute or must correspond to a valid lang code for multilingual screen reader users who may prefer a language other than the default. The xml:lang attribute value, if included on the html element, must duplicate the value of the lang exactly.
ID attribute value must be unique.
The value assigned to the ID attribute on focusable elements must be unique to prevent the second instance from being overlooked by assistive technology. Put another way, ID attributes may not be used more than once on focusable elements in the same document in order to differentiate each focusable element from another.
ID attribute values must be unique.
The value assigned to an ID attribute must be unique to prevent the second instance from being overlooked by assistive technology. Put another way; ID attributes may not be used more than once in the same document to differentiate each element from another.
IDs used in ARIA and labels must be unique.
The value assigned to an ARIA ID must be unique to prevent the second instance from being overlooked by assistive technology. Put another way; ARIA ID values may not be used more than once in the same document to differentiate each element from another.
Image buttons must have alternate text.
Ensures input type='image' elements have alternate text.
Images must have alternate text.
All images must have alternate text to convey their purpose and meaning to screen reader users.
lang attribute must have a valid value.
The language specified in the HTML document must be one of the valid languages to ensure text is pronounced correctly for screen reader users.
Layout tables must not use data table elements.
If a table is being used for layout purposes only, it must not use data table elements such as a header, caption, and summary to prevent confusion by screen reader users who would otherwise expect data to be contained within the cells.
li elements must be contained in a ul or ol.
All list items (li) must be contained within ul or ol parent elements.
Links must be distinguished from surrounding text in a way that does not rely on color.
Ensures users who cannot distinguish between colors can tell when text is a link by verifying the link has either a distinct style that does not rely on color or has a contrast difference of greater than 3:1 (which alerts you that manual testing is required).
Links must have discernible text.
Link text and alternate text for images, when used as links, must be discernible by a screen reader, must not have a duplicate label, and must be focusable.
Main landmark must not be contained in another landmark.
It is a best practice to ensure the main landmark is not contained within another landmark. All content should be contained within distinct regions such as the header (role='banner'), content (role='main'), and footer (role='contentinfo').
marquee elements are deprecated and must not be used.
marquee elements must not be present because they are deprecated, increase difficulty for users with limited dexterity, and are distracting for users with cognitive or attention deficits.
object elements must have alternate text.
All embedded objects must have text alternatives to be read out to screen reader users.
Page must contain a level-one heading.
Ensures that the page, or at least one of its frames contains an h1 element that appears before the start of the main content to allow screen reader users to use keyboard shortcuts to navigate the heading structure instead of wasting time listening to more of the web page to understand its structure.
Page must have means to bypass repeated blocks.
Each page must have a main landmark to provide a mechanism to bypass repeated blocks of content or interface elements (like header and navigation) and quickly arrive at the main content.
Page must have one main landmark.
It is a best practice to ensure that there is only one main landmark to navigate to the primary content of the page and that if the page contains iframe elements, each should either contain no landmarks, or just a single landmark.
Page must not have more than one banner landmark.
Ensures the page has at most one banner landmark.
Page must not have more than one contentinfo landmark.
Ensures the page has at most one contentinfo landmark.
Radio inputs with the same name attribute value must be part of a group.
Radio buttons that relate to each other must share a common label.
Required ARIA attributes must be provided.
ARIA widget roles must have appropriate attributes describing the state or properties of the widget.
Scope attribute should be used correctly on tables.
The scope attribute must be used correctly on tables in accordance with either HTML4 or HTML5 specifications to enable efficient table navigation for screen reader users.
Server-side image maps must not be used.
The document contains an image map that is server-side instead of client-side.
Text elements must have sufficient color contrast against the background.
All text elements must have sufficient contrast between text in the foreground and background colors behind it in accordance with WCAG 2 AA contrast ratio thresholds.
Text of buttons and links should not be repeated in the image alternative.
When button and link text repeats in a alt attribute value, screen reader users hear the same information twice, which renders the alt text meaningless and confusing.
The caption element should not contain the same text as the summary attribute.
Data table markup can be tedious and confusing. Make sure caption and summary table attributes are not identical. Screen readers have some features to manage table navigation, but tables must be marked up accurately for these features to work correctly.
The skip-link target should exist and be focusable.
The page must have a link at the top before the navigation that allows users to skip lengthy navigation and proceed to a page's main content to save time.
Timed refresh must not exist.
The document must not use meta http-equiv='refresh' because it can prevent control over when the refresh occurs for users with disabilities.
ul and ol must only directly contain li, script or template elements.
Lists must be marked up correctly, meaning they must not contain content elements other than li elements.
Unsupported DPUB ARIA roles should be used on elements with implicit fallback roles.
When a Digital Publishing Role that is not supported is conveyed via a role attribute value, semantic information can only be conveyed to screen reader users via native HTML elements that have similar semantics for fallback.
Users should be able to zoom and scale the text up to 500%.
The document must not use the user-scalable='no' parameter in the meta name='viewport' element because it disables text scaling and zooming which is essential to users with low vision.
video elements must have a track for captions.
An HTML5 video element must include a track element with kind='captions' set as a property. The captions should convey all meaningful auditory information in the video including dialogue, musical cues, sound effects, and other relevant information for deaf users.
video elements must have an audio description track.
The HTML5 video element must have an audio description track to provide blind users with information the dialogue does not.
Zooming and scaling must not be disabled.
The document must not use the user-scalable='no' parameter in the meta name='viewport' element because it disables text scaling and zooming which is essential to users with low vision.
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