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 - Online Check Structure & Errors
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.
URLs copied to clipboard!
YAML Validator & Formatter - Online Check Syntax
Validate YAML syntax with line‑by‑line error messages. Also format messy YAML into clean, indented output. All in your browser.
SQL Syntax Validator - Online Quick Check
Paste your SQL query and check for basic syntax errors. Highlights missing commas, wrong keywords. Local analysis.
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.
Percent Error & Relative Error Calculator - Online Lab Report Tool
Calculate absolute error, relative error, and percent error between experimental and theoretical values. For science students. Instant local math.
Assertive Statement Composer – Online I-Statements Tool
Build 'I feel... when... because...' statements interactively. Improve communication in relationships. Local only.
Palindrome Tester - Online Phrase Checker
Enter any phrase and instantly see if it's a palindrome, ignoring spaces and punctuation. Fun for word nerds.
Intentional Typo Generator - Online Missssspell Tool
Take a perfectly fine phrase and insert realistic-looking typos. For pranks or testing spell‑checkers.
Palindrome Checker - Online Test Words & Sentences
Check if a word or phrase is a palindrome (reads same forward and backward). Live validation and fun facts.
Synonym Chain Builder - Online Word Association Game
Start with a word and find synonyms, then synonyms of synonyms. Build a chain and explore language. Local thesaurus.
Keyboard Accessibility Tester – Online Check Tab Order
Paste HTML snippet and see calculated tab order. Identify missing focusable elements. A11y helper.
Fake Company Slogan Generator - Online Creative Tagline
Generate a random, funny or serious company slogan for your startup idea. Brainstorming helper. All local.
Golf Handicap Differential Calculator – Online Score to Index
Enter adjusted gross score, course rating, and slope to calculate the round's handicap differential. Track your index.
Error Function (erf) Calculator - Online Statistics & Physics
Compute the error function and complementary error function for any real x. Quick and precise. Pure frontend math.
Tint & Shade Generator - Online Lighter & Darker Colors
Generate tints (add white) and shades (add black) for any base hex color. Copy values for design systems. Instant local generation.
SQL JOIN Temperature Tester - Online Quick Join Syntax Checker
Quickly test SQL JOIN syntax (INNER, LEFT, RIGHT, FULL) with a sample database schema. Check logic and see conceptual result set without a real DB. Local only.
Mock Sentence Generator - Online SaRcAsM wRiTiNg
Turn any sentence into mocking SpongeBob‑style text. Choose intensity. Copy and paste into chats. Pure client.
Camping Gear Checklist – Online Custom by Trip Type
Generate a camping checklist based on trip style (car, backpacking, glamping). Check off items. Fully local.
Data Table to Markdown - Online Paste & Format
Paste tab‑separated or CSV data and instantly get a beautifully aligned Markdown table. Essential for documentation.
Golf Handicap Calculator - Online Quick Index Estimator
Enter recent scores, course rating, and slope to estimate a golf handicap index. Simple formula for unofficial tracking. Local only.
Ski Binding DIN Calculator – Online Weight, Height, BSL, Skier Type
Enter your weight, height, boot sole length, and skier type to see the recommended DIN release setting.
Random MAC Address Generator - Online Hardware Test IDs
Generate valid, random unicast MAC addresses for testing or spoofing. Select OUI prefix if desired. Local only.
Unit Price Comparison Table - Online Shopping Helper
Enter products with different prices and weights/volumes. The tool ranks them by best value per unit. Save money effortlessly.
commandfor & command Attribute Demo - Online Declarative Actions
Use the new `commandfor` and `command` attributes to invoke actions on other elements without JavaScript. See the spec live.
Text to Binary Converter - Online ASCII Bit Translator
Convert any text into its binary representation (8-bit per character). See the raw bits. Suitable for learning computer fundamentals. All local.
Color Harmony Chooser - Online Complementary & Triadic
Find complementary, triadic, analogous, and split-complementary color combinations. Interactive color wheel. Essential for UI design.
First Aid Kit Checklist – Online Printable Basic & Advanced
Generate a comprehensive first aid kit list for home, car, or hiking. Check off what you have.
Scattergories List Generator - Online Categories & Letter Roll
Generate random Scattergories‑style lists with a random letter and 12 categories. Great for online game night.
Rabbit Color Genetics Calculator – Online Predict Kit Colors
Select parent colors and genotypes to predict possible offspring coat colors. Based on simple Mendelian genetics for common breeds.
Text to Guitar Tablature Converter - Online ASCII Tab Maker
Enter notes or chords on a virtual fretboard and generate ASCII tablature. Quick way to share musical ideas.