HTML lang Validator - Online Check Language Tag
Validate a language tag like en‑US or zh‑Hans against the IANA registry. Ensure correct HTML lang attribute.
UD5 Toolkit
Validate ARIA attributes, roles, and accessibility patterns in your HTML code. Detect errors, warnings, and get actionable fix suggestions.
<button> instead of <div role="button">).aria-label, aria-labelledby, or native labeling techniques.aria-label provides a direct string value as the accessible name for an element (e.g., aria-label="Close dialog").
aria-labelledby references the ID(s) of other elements whose text content serves as the accessible name (e.g., aria-labelledby="title-id desc-id").
aria-labelledby takes precedence over aria-label when both are present. Use aria-labelledby when the label text already exists in the DOM; use aria-label when no visible label is present.
aria-hidden="true" to hide decorative or redundant content from assistive technologies while keeping it visible on screen. Common use cases include: decorative icons, duplicated content, off-screen collapsed menus, and purely visual elements. Never apply aria-hidden="true" to focusable elements or their ancestors, as this creates a confusing experience where a screen reader user can focus on an element that is "invisible" to them.
role="dropdown" (use role="listbox" or role="menu" instead).aria-label or aria-labelledby.aria-labelledby or aria-controls pointing to non-existent IDs.<div role="button"> instead of <button>.aria-expanded on collapsible triggers, or missing aria-selected on tabs.banner, navigation, main, complementary, contentinfo, search, form, region) allow screen reader users to quickly jump between major page sections. Each landmark should be unique when possible and properly labeled using aria-label or aria-labelledby (especially when multiple landmarks of the same type exist, like multiple navigation regions). Using HTML5 semantic elements like <nav>, <main>, and <footer> automatically provides landmark roles.
aria-live informs assistive technologies about dynamic content changes so they can announce updates to the user. Values include: off (default, no announcement), polite (announces when user is idle), and assertive (announces immediately, interrupting current speech). Use aria-live="polite" for most updates (like form validation messages) and aria-live="assertive" sparingly for critical alerts. Pair with aria-atomic and aria-relevant for finer control.
Validate a language tag like en‑US or zh‑Hans against the IANA registry. Ensure correct HTML lang attribute.
Create a fully accessible form by adding fields; the tool generates the proper labels, inputs, and ARIA attributes. Copy the clean HTML.
Convert plain text into HTML‑safe strings by escaping <, >, &, and quotes. Insert into code safely. Local copy.
Paste a WebVTT file and instantly check for syntax errors. Validate timestamps and cue formatting. Essential for video devs.
Convert English text to Braille (Grade 1 and simple Grade 2 contractions). Educational tool to understand Braille representation. Local only.
Fetch a site’s HSTS header and validate its syntax, max‑age, and subdomain flags. Ensure your site enforce HTTPS.
Calculate the perceived brightness of an RGB color and determine if black or white text is more readable. Accessibility tool.
Enter original and target color to compute the exact CSS hue‑rotate(deg) filter needed. For precise icon and image tinting.
Request HID devices and list them. Read input reports and send output. For custom hardware and controllers.
Start with a base color and generate an extended palette where every shade contrasts properly with white and black. Export tokens.
Pick colors using the HWB (Hue‑Whiteness‑Blackness) model. Get the CSS hwb() function code. Simpler than HSL for some.
Pick a base color and generate a 10‑step scale where each step meets a specific contrast ratio against white or black. Export as CSS custom properties.
Convert carabiner strength from kN to kg/lbs and understand Major Axis vs Minor Axis markings. Quick educational reference for climbers.
Enter any number up to trillion and get the English word representation. For filling out checks or legal documents.
See how a PWA can extend content into the title bar area on desktop. Customize the window controls overlay.
Enter pot volume and tea type to find the right amount of dry leaf considering expansion. Avoid overflowing.
Upload any image, add a thick white border and drop shadow, and turn it into a sticker. Download as transparent PNG.
Test the experimental Translation API to translate text between languages directly in the browser, without cloud calls. Check support and copy the JavaScript starter.
Automatically restore natural colors to a photo by removing color casts. Gray world algorithm. One‑click fix. Canvas.
Search common dream symbols and their traditional meanings. For entertainment and self-reflection. Static data.
Follow along with animated crease patterns to fold a paper crane. Pause and rewind steps.
Shift the color temperature of your photo towards warm (orange) or cool (blue). Instant canvas filter. Download result.
Click colors on an interactive wheel and see the common emotions and meanings associated with them. A design resource.
Simulate how images and UI elements appear to users with various types of color blindness. Upload or paste image URL. Promote inclusive design.
Convert volume and capacity units: gallon (US/UK), liter, milliliter, cup, and fluid ounce. Handy for cooking and science. Works entirely offline.
Enter current weight and age to estimate adult weight based on growth curves. For purebred and mixed.
Reverse entire text, flip letters, or reverse word order. Fun for puzzles and creative writing. Instant transformation without data leaving your browser.
Estimate the baby's due date based on last menstrual period (LMP) or conception date. Also shows current week and trimester. Educational only.
Click any color to see common emotional associations and cultural meanings. Quick design reference.
Draw a digit (0‑9) on the canvas and a simple neural net guess the number. Educational demo. No upload.