Text Contrast Validator - Online WCAG AAA Checker
Enter a text color and background color and instantly see if the combination passes WCAG AA and AAA ratio. Safe colors.
UD5 Toolkit
Enter a text color and background color and instantly see if the combination passes WCAG AA and AAA ratio. Safe colors.
Paste robots.txt content and parse it to check validity, find disallowed paths. Educational SEO tool. Local processing.
Paste your sitemap XML and check for missing namespaces, invalid URLs, or size limit violations. Keep your SEO healthy.
Paste JSON-LD and validate basic syntax and required properties for Article, Product, etc. Local only. Instant feedback.
Paste a GeoJSON object and validate its structure. Catch missing coordinates, wrong types, and feature errors. Local.
Paste your manifest.json and instantly validate it against the W3C spec. Catch errors and warnings. Client‑side.
Paste HTML snippet and highlight interactive elements missing accessible labels. Quick a11y audit.
Paste a media query and instantly check for syntax errors. See if it's correctly formed. Quick developer tool.
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.
Paste a WebVTT file and instantly check for syntax errors. Validate timestamps and cue formatting. Essential for video devs.
Validate a language tag like en‑US or zh‑Hans against the IANA registry. Ensure correct HTML lang attribute.
Enter a URL and a user‑agent to see if it is allowed or blocked by the robots.txt file. Quick bot validation.
Validate and compare semantic version strings. Check if a version satisfies a range (e.g., ^1.2.3). Visual breakdown of major.minor.patch. Local only.
Enter a UPC or EAN barcode number and validate the check digit. See if it's a real product code. Local calculation.
Paste an HTML snippet and check for common ARIA mistakes: missing labels, invalid roles, and aria‑hidden misuse. Educate your team.
Validate a DNSSEC chain by entering DS and RRSIG records. Verify that signatures match. Educational. Local algorithm.
Check and beautify your TOML config files. Highlights errors and aligns tables and arrays. Safe local parsing.
Paste your .htaccess rules and check for common syntax errors or misconfigurations. No server required; static analysis.
Paste any DNS record and check if its format is valid for the selected record type (A, AAAA, CNAME, MX, TXT, SRV). Prevents typos.
Send conditional requests to a URL and verify that the server correctly handles ETag and If‑None‑Match. Audit caching.
Paste a Bitcoin, Ethereum, or other crypto wallet address and quickly verify its format and checksum. No connection to blockchain.
Validate YAML syntax with line‑by‑line error messages. Also format messy YAML into clean, indented output. All in your browser.
Paste a robots.txt file and validate its syntax. See if a specific user‑agent can access a path. Essential for webmasters.
Paste Markdown and get warnings for common mistakes: inconsistent heading spacing, bare URLs, and broken links. All local.
Check if an IBAN has the correct length and structure for its country. Early validation, no bank connection.
Validate if a version string follows SemVer 2.0.0. Also sort and compare versions. Developer tool.
Paste your SQL query and check for basic syntax errors. Highlights missing commas, wrong keywords. Local analysis.
Paste a string and verify if it is valid Base64. Auto‑detects padding issues and character errors. Quick dev check.
Paste a test card number to verify Luhn algorithm, identify issuer (Visa, MC), and check length. No real data.
Paste a list of numbers to visually check uniformity, mean, and simple pattern analysis. Educational tool for statistics and RNG.
Validate ISBN‑10 and ISBN‑13 numbers and compute their check digits. Useful for booksellers and libraries. All local.
Easily format, validate, and beautify XML documents. Minify XML data with a single click. All processing happens locally in your browser for maximum privacy.
Online JSON formatting and validation tool, supporting JSON minify/beautify, syntax highlighting, and error locating. Data processed locally in browser for security.