ARIA Attribute Validator — Check Names, Values and References

An ARIA validator online checks HTML markup for certain accessibility attribute problems, including unsupported ARIA names, invalid state values, references to nonexistent IDs, duplicate IDs and selected conflicting states. Paste a representative HTML snippet, review the element-level findings and download the report. These are limited static checks against a defined reference subset. They cannot confirm that controls respond correctly to a keyboard, that a screen reader announces the intended accessible name, or that the completed interface meets WCAG requirements.

ARIA Validator Online At a Glance

What ARIA Attributes Mean for Accessible Interfaces

Accessible Rich Internet Applications attributes communicate additional semantics and states when native HTML does not express everything a component needs. An aria-expanded value can describe whether a menu is open, aria-controls can associate a trigger with a controlled element, and aria-labelledby can specify which text provides an accessible name. These attributes do not automatically make an interface accessible. A control that claims aria-expanded=true while the menu remains closed can mislead users of assistive technology, and a visually obvious icon can still lack a usable name if references are broken.

The first design decision is whether ARIA is needed at all. Native buttons, inputs, labels, headings and tables already provide important behavior and semantics. Replacing them with div elements and attributes often creates new keyboard and state-management obligations. This validator helps inspect explicit ARIA statements in a pasted fragment, but it cannot infer every interaction contract from markup alone. A good component starts with appropriate native HTML, adds only necessary attributes, and updates them consistently with what the interface actually does.

Validating Boolean, Enumerated and Numeric Values

Many ARIA properties require constrained values rather than arbitrary words. For example, aria-hidden normally expects true or false, aria-live expects off, polite or assertive, and aria-current accepts a defined set that includes page, step and date. A typo such as aria-expanded="open" is therefore suspicious even when the intended meaning seems clear to a person reading the source. The validator checks selected properties against known sets and reports invalid values, helping catch mistakes that could otherwise survive visual QA.

Numeric attributes also have meaningful restrictions. aria-level should be a positive integer, and a slider's aria-valuenow should fall between its stated minimum and maximum when those limits exist. Static value rules can detect impossible combinations in supplied markup but cannot determine whether the selected value reflects the current application state. A slider might expose a valid aria-valuenow of 50 while its visible thumb represents 70. That discrepancy requires interacting with the real control rather than inspecting the initial HTML alone.

ID References and Accessible Names

Attributes such as aria-labelledby, aria-describedby and aria-controls rely on element IDs. If an attribute points to an ID absent from the supplied HTML, the user agent may be unable to find the intended label, description or controlled panel. The validator checks whether referenced IDs exist and flags missing names as errors. It also reports duplicate IDs, because an identifier that appears more than once creates ambiguity and can produce inconsistent relationships. A snippet must include the referenced element to avoid a false missing-ID report for content that lives outside the pasted fragment.

Even when the referenced IDs exist, the resulting accessible name may not be correct. Hidden text, nested markup, punctuation and multiple references influence what assistive technologies announce. The checker does not perform the accessible-name computation algorithm or speak the result through a screen reader. Use the generated findings to correct obvious references, then inspect the completed component with browser accessibility tooling and a representative screen reader. A valid relationship is necessary in many cases but is not proof of a meaningful accessible label.

ARIA Roles and Compatibility with Native HTML

A role describes the kind of widget or region an element represents, such as tab, button, dialog or navigation. This tool compares role tokens against a limited list of familiar roles, but that is only a syntax and recognition check. It does not fully validate prohibited role-attribute combinations, the implicit semantics of each HTML element or whether required owned child roles exist. A recognized role can still be used incorrectly. For example, giving a decorative span the role of button does not supply focusability or keyboard activation; those behaviors require deliberate implementation.

When a native element provides the intended role, unnecessary overrides should be avoided. A real button is generally preferable to an element that merely declares role="button". If a design requires a custom composite widget, test focus movement, arrow-key expectations, disabled states and state announcements as part of the component contract. The HTML-to-plain-text converter can show a rough textual reading order, but it cannot represent ARIA semantics or replace assistive-technology testing.

Worked Example: A Menu Button with a Broken Reference

Suppose a button contains aria-expanded="false" and aria-controls="account-menu", but the only associated panel has id="profile-menu". The validator identifies that the controls reference has no matching ID in the provided fragment. Correcting either the button reference or panel ID restores the structural relationship. If the panel is conditionally rendered only after interaction, paste a representative state that includes it, or interpret the finding as needing follow-up rather than automatically declaring the whole page broken.

Next, imagine that the button uses aria-expanded="sometimes". That string is not a recognized value and should be replaced with the state that truly corresponds to the interface, usually true or false for an expandable trigger. After the static change, click the button using a keyboard, confirm the panel visibility changes, and ensure the attribute changes with it. Static markup with a valid initial value does not ensure runtime synchronization, which is why the tool separates code-level findings from actual usage checks.

Hidden Elements and Keyboard Focus

The aria-hidden attribute removes content from the accessibility tree when it is set to true. Problems arise if a keyboard-focusable control remains inside or on an element that assistive technology can no longer describe. The validator warns about a small number of obvious cases, such as a directly focusable button marked aria-hidden=true. This warning is not a complete descendant-tree analysis, nor does it model CSS display rules, inert behavior or script-driven focus management. Some elements may be visually hidden while still exposed in the accessibility tree, and others behave differently depending on application state.

Focus traps and reading order deserve separate examination. A dialog may have valid role and aria-modal attributes while allowing focus to escape behind the overlay, and a tab interface may have correct selected-state values but unusable arrow-key behavior. Test keyboard navigation with the actual running interface. Inspect focus visibility at different zoom levels and make sure controls do not disappear from the user's perception while remaining reachable by Tab. HTML attribute validation is only one component of that practical review.

Parsing Pasted HTML without Executing It

The workspace uses a browser HTML parser to construct an inert document from supplied markup. It reads tag names, IDs and attributes for static analysis and does not inject the pasted HTML into the visible page as executable content. This avoids turning an accessibility check into an opportunity to run scripts from an unknown snippet. The parser may repair malformed HTML according to browser rules, so the element structure being checked can differ from a raw string containing mismatched tags. If the syntax itself is broken, first correct the HTML in the original source and inspect the browser's resulting document tree.

Only a bounded number of elements are accepted so a huge fragment does not overwhelm the result table. Element positions refer to the parsed element list, not exact lines in an editor or source-map locations in a compiled application. The JSON report contains issue messages and indices, which can support a developer's checklist but cannot identify the original component file automatically. For that, maintain a clear mapping between copied snippets and their source modules.

Accessibility Conformance Requires More than ARIA Syntax

A website can use flawless ARIA values and still fail important requirements for text contrast, keyboard access, focus order, captions, form instructions or readable error messages. Conversely, a simple page built from semantic HTML may need very few explicit ARIA attributes. The validator is most valuable as a targeted code review aid rather than a substitute for a representative accessibility audit. Use its findings alongside manual tests, automated accessibility engines and checks with users who rely on assistive technology when feasible.

Review multiple component states instead of only the initial screen. An error message may appear after form submission; a menu may become expanded; a tab may activate a different panel; and an asynchronous status may update after loading completes. Each state can carry different accessibility relationships. A reliable release process records the version tested, the browser and assistive technology used, and the observed result. No message such as “zero errors” should be interpreted as evidence that the overall interface is fully accessible.

Frequently Asked Questions About ARIA Validator Online

Conclusion

Fix each reported attribute or reference in the original component, then test the actual interaction state with a keyboard and assistive technology. Correct values matter, but meaningful semantics, reliable focus and understandable announcements determine whether an interface is usable.