ARIA Attribute Validator - Online Check HTML Accessibility
Paste an HTML snippet and check for common ARIA mistakes: missing labels, invalid roles, and aria‑hidden misuse. Educate your team.
UD5 Toolkit
Paste your HTML and instantly find missing ARIA labels, accessibility gaps, and WCAG violations.
WCAG 2.1 Compliant ChecksPaste your HTML and click "Analyze HTML" to check for accessibility issues.
Or click "Load Sample" to see a demo with common ARIA mistakes.
aria-label, aria-labelledby, and the native <label> element for form controls.
<button>, <a> (with href), <input>, <select>, <textarea>, and any element with interactive ARIA roles such as role="button", role="link", role="checkbox", role="radio", role="switch", role="tab", role="menuitem", and more. Additionally, <img> elements must have an alt attribute (even if empty for decorative images). Non-interactive elements like <div> or <span> typically do not need ARIA labels unless they have been given an interactive role.
aria-label provides a direct string value as the accessible name, e.g., aria-label="Close dialog". In contrast, aria-labelledby references the ID(s) of other elements whose text content should be used as the accessible name, e.g., aria-labelledby="heading-id". Use aria-labelledby when visible text already exists on the page that can serve as the label. Use aria-label when no visible label text is available. aria-labelledby takes precedence over aria-label when both are present.
aria-label are invisible to screen readers.alt on images: Every <img> must have an alt attribute. Use alt="" for purely decorative images.aria-label: An aria-label="" is treated as having no label, effectively hiding the element from assistive technology.aria-labelledby references: Referencing an ID that doesn't exist in the DOM.<label>: Relying solely on placeholder text is not sufficient for accessibility.aria-label with a descriptive name. For example:<button aria-label="Search"><i class="fa fa-search"></i></button>.sr-only or visually-hidden class, that text will serve as the accessible name. If a visible tooltip or adjacent text exists, you can use aria-labelledby to point to it. For buttons that toggle state (like a hamburger menu), include the state in the label: aria-label="Open menu" and update it to aria-label="Close menu" when toggled.
alt="" (empty alt attribute) is perfectly valid and is the correct way to mark an image as decorative. Screen readers will skip images with empty alt text, which reduces noise for users. However, if the image conveys meaningful information or is part of a link/button, it must have a descriptive alt value. Our tool distinguishes between missing alt (an error) and empty alt (generally acceptable, shown as informational).
placeholder attribute is not a substitute for a proper <label> element or aria-label. Placeholder text disappears once the user starts typing, has poor color contrast in many designs, and is not consistently announced by all screen readers. Always pair form inputs with a visible <label> using the for attribute, or wrap the input inside the label. If a visible label is not desired for design reasons, use aria-label or a visually-hidden label.
Paste an HTML snippet and check for common ARIA mistakes: missing labels, invalid roles, and aria‑hidden misuse. Educate your team.
Create a fully accessible form by adding fields; the tool generates the proper labels, inputs, and ARIA attributes. Copy the clean HTML.
Paste an SVG and check if the graphic‑aria roles are used correctly. Improve accessible diagrams and icons.
Enter a text color and background color and instantly see if the combination passes WCAG AA and AAA ratio. Safe colors.
Validate a language tag like en‑US or zh‑Hans against the IANA registry. Ensure correct HTML lang attribute.
Paste JSON-LD and validate basic syntax and required properties for Article, Product, etc. Local only. Instant feedback.
Enter a UPC or EAN barcode number and validate the check digit. See if it's a real product code. Local calculation.
Enter a URL and fetch its Twitter card meta tags. See a live preview of how the tweet will appear. Debug social sharing.
Paste JavaScript and catch syntax errors instantly with line numbers. Lightweight pre‑commit check. Local.
Paste HTML and detect unclosed tags, invalid nesting, and duplicate IDs. Lightweight client‑side validation.
Watch for updates to aria‑live regions and log what a screen reader would announce. Debug live regions.
Send conditional requests to a URL and verify that the server correctly handles ETag and If‑None‑Match. Audit caching.
Enter a URL and a user‑agent to see if it is allowed or blocked by the robots.txt file. Quick bot validation.
Enter a URL and see a list of its ARIA landmarks (banner, main, nav). Check document structure for accessibility. Local fetch.
Paste a media query and instantly check for syntax errors. See if it's correctly formed. Quick developer tool.
Inject dynamic messages into ARIA live regions and monitor how they trigger screen reader announcements. Debug a11y.
Validate a DNSSEC chain by entering DS and RRSIG records. Verify that signatures match. Educational. Local algorithm.
Paste any DNS record and check if its format is valid for the selected record type (A, AAAA, CNAME, MX, TXT, SRV). Prevents typos.
Paste your SQL query and check for basic syntax errors. Highlights missing commas, wrong keywords. Local analysis.
Paste a Bitcoin, Ethereum, or other crypto wallet address and quickly verify its format and checksum. No connection to blockchain.
Check and beautify your TOML config files. Highlights errors and aligns tables and arrays. Safe local parsing.
Validate YAML syntax with line‑by‑line error messages. Also format messy YAML into clean, indented output. All in your browser.
Validate ISBN‑10 and ISBN‑13 numbers and compute their check digits. Useful for booksellers and libraries. All local.
Check if an IBAN has the correct length and structure for its country. Early validation, no bank connection.
Paste a test card number to verify Luhn algorithm, identify issuer (Visa, MC), and check length. No real data.
Validate if a version string follows SemVer 2.0.0. Also sort and compare versions. Developer tool.
Paste Markdown and get warnings for common mistakes: inconsistent heading spacing, bare URLs, and broken links. All local.
Paste a robots.txt file and validate its syntax. See if a specific user‑agent can access a path. Essential for webmasters.
Design simple text‑based labels and print them on standard Avery label sheets. Choose from common templates.
Paste a string and verify if it is valid Base64. Auto‑detects padding issues and character errors. Quick dev check.