UD5 Toolkit
HTML Validator Lite - Online Check Syntax Errors
Paste HTML and detect unclosed tags, invalid nesting, and duplicate IDs. Lightweight client‑side validation.
XML Sitemap Validator
Validate your XML sitemap structure, detect errors, check protocol compliance, and ensure search engines can properly crawl your URLs.
Due to CORS restrictions, fetching remote sitemaps may fail. If so, please copy the sitemap content and use the Paste XML tab.
Frequently Asked Questions
What is an XML Sitemap?
An XML sitemap is a file that lists all important URLs of your website, helping search engines like Google, Bing, and Yahoo discover and index your content more efficiently. It follows the Sitemaps protocol standard.
How do I find my sitemap?
Common locations include /sitemap.xml, /sitemap_index.xml, or check your robots.txt file (e.g., https://yoursite.com/robots.txt) for a Sitemap: directive. CMS platforms like WordPress often generate sitemaps automatically via plugins like Yoast SEO or Rank Math.
What are common sitemap errors?
Frequent issues include: invalid XML syntax (unclosed tags, special characters not escaped), missing <loc> elements, incorrect namespace declarations, invalid date formats in <lastmod>, out-of-range priority values (must be 0.0–1.0), and duplicate URLs.
What are the size limits?
A single sitemap file must not exceed 50MB (uncompressed) and can contain at most 50,000 URLs. If your site exceeds these limits, use a Sitemap Index file to split URLs across multiple sitemap files.
What is a Sitemap Index?
A Sitemap Index file (root element <sitemapindex>) references multiple individual sitemap files. Each <sitemap> entry contains a <loc> pointing to a child sitemap. This allows large websites to organize URLs across many files while staying within protocol limits.
How to submit a sitemap to search engines?
Submit via Google Search Console (Index → Sitemaps), Bing Webmaster Tools, or add a Sitemap: directive in your robots.txt. You can also ping search engines directly: https://www.google.com/ping?sitemap=YOUR_SITEMAP_URL.
How often should I update my sitemap?
Update your sitemap whenever you add, remove, or significantly modify important pages. For dynamic sites (e.g., e-commerce, news), consider automated daily regeneration. Use the <lastmod> and <changefreq> tags to signal update frequency to crawlers.
Does a valid sitemap guarantee indexing?
No. A valid sitemap helps search engines discover your URLs, but indexing depends on content quality, crawl budget, canonical signals, and other ranking factors. Always pair a clean sitemap with proper internal linking and high-quality content for best results.
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UPC Barcode Validator - Online Check Digit & EAN
Enter a UPC or EAN barcode number and validate the check digit. See if it's a real product code. Local calculation.
Event Schema Markup Generator - Online JSON‑LD for Concerts
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Twitter Card Previewer - Online See How Tweets Render
Enter a URL and fetch its Twitter card meta tags. See a live preview of how the tweet will appear. Debug social sharing.
ETag & Last‑Modified Validator - Online Check Cache Headers
Send conditional requests to a URL and verify that the server correctly handles ETag and If‑None‑Match. Audit caching.
CSS Media Query Syntax Checker - Online Validator
Paste a media query and instantly check for syntax errors. See if it's correctly formed. Quick developer tool.
DNSSEC Chain Validator - Online Check RRSIG & DS
Validate a DNSSEC chain by entering DS and RRSIG records. Verify that signatures match. Educational. Local algorithm.
DNS Record Syntax Checker - Online Validate BEFORE Publishing
Paste any DNS record and check if its format is valid for the selected record type (A, AAAA, CNAME, MX, TXT, SRV). Prevents typos.
SQL Syntax Validator - Online Quick Check
Paste your SQL query and check for basic syntax errors. Highlights missing commas, wrong keywords. Local analysis.
Keyword Extractor - Online Rapid Text Analysis
Paste any article and get a list of the most relevant keywords using a simple TF‑IDF‑like model. Skip stop words. All local.
ISBN Validator - Online Check ISBN‑10 & ISBN‑13
Validate ISBN‑10 and ISBN‑13 numbers and compute their check digits. Useful for booksellers and libraries. All local.
Live Website Audit Checker - Online Quick SEO & Performance
Enter a URL and get a one‑page report of titles, description, headings, image alts, and broken links. All from browser.
IBAN Structure Checker - Online Validate Format & Country
Check if an IBAN has the correct length and structure for its country. Early validation, no bank connection.
Test Credit Card Validator - Online Luhn Check & Issuer
Paste a test card number to verify Luhn algorithm, identify issuer (Visa, MC), and check length. No real data.
HTML Outline Extractor - Online Heading Map from URL
Enter a URL and see a nested list of all h1‑h6 tags. Check document structure for SEO and accessibility.
Favicon Checker - Online Test Any Site's Icon
Enter a URL and see its favicon at all standard sizes. Check if it's properly defined. SEO basic check.
Semantic Versioning Validator - Check Semver Syntax
Validate if a version string follows SemVer 2.0.0. Also sort and compare versions. Developer tool.
Markdown Linter - Online Check Syntax & Style
Paste Markdown and get warnings for common mistakes: inconsistent heading spacing, bare URLs, and broken links. All local.
HTTP Redirect Path Tracer - Online SEO Chain Analyzer
Trace the full redirect path of a URL. See every hop, status code, and final destination. Detect broken chains.
Robots.txt Validator - Online Check Syntax & Rules
Paste a robots.txt file and validate its syntax. See if a specific user‑agent can access a path. Essential for webmasters.
Advanced Slug Generator - Online Custom Separator & Language
Convert title to URL slug with options: ignore stop words, transliterate special characters, choose separator. SEO friendly.
Base64 String Validator - Online Check Valid Encoding
Paste a string and verify if it is valid Base64. Auto‑detects padding issues and character errors. Quick dev check.
PRNG Validator - Online Check Randomness Pattern
Paste a list of numbers to visually check uniformity, mean, and simple pattern analysis. Educational tool for statistics and RNG.
Meta Tag Extractor - Online View Any Page's SEO Tags
Fetch and extract all meta tags, open graph tags, and Twitter cards from a live URL. No server proxy, direct browser fetch.
Redirect Path Tracer - Online SEO Redirect Chain Analyzer
Enter a URL and trace the full redirect chain, seeing each hop's status code and location. Identify unnecessary redirects. Client-side fetch.
Keyword Density Checker - Online SEO Text Analyzer
Analyze text for keyword frequency and density. Highlights over-optimized terms. Perfect for content writers and SEO editors. Entirely browser-based.
Robots.txt Generator - Online Create & Validate Robots File
Build a properly formatted robots.txt file with user-agent rules and sitemap location. Validate syntax in real time. Essential for webmasters.
XML Sitemap Generator - Online Free Website Sitemap Builder
Generate a standard XML sitemap for your website by entering a start URL. Crawls internal links directly from your browser. No server-side processing.
XML Formatter & Validator - Free Online XML Beautifier
Easily format, validate, and beautify XML documents. Minify XML data with a single click. All processing happens locally in your browser for maximum privacy.
JSON Formatter & Validator - Online JSON Beautifier
Online JSON formatting and validation tool, supporting JSON minify/beautify, syntax highlighting, and error locating. Data processed locally in browser for security.