Web tools
Tools for people who run websites: build meta tags and sitemaps, tag campaign links, write redirect rules, test robots.txt rules and read HTTP headers.
- Web
Email address validator
Check email address syntax line by line using practical RFC 5321 and 5322 rules, with a reason for each failure. It cannot check whether a mailbox exists.
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HTTP header parser
Parse pasted HTTP request or response headers into a table, combine duplicates, and explain which security and caching headers are present or missing.
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Cookie header parser
Parse a Cookie request header into name and value pairs, or Set-Cookie lines into their attributes, with warnings such as SameSite=None without Secure.
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Robots.txt tester
Test whether a robots.txt allows a crawler to fetch a URL path using RFC 9309 rules, show the deciding rule and list any sitemaps. Paste the file; nothing is fetched.
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Meta tag generator
Build HTML head tags for title, description, canonical URL, robots, viewport, charset and theme color, safely escaped, with length warnings.
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Open Graph tag generator
Build escaped Open Graph and Twitter card meta tags for link previews: title, description, URL, image with alt text and size, type, site name and card.
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Sitemap XML generator
Turn a list of URLs into a sitemap.xml urlset with optional lastmod, changefreq and priority. Checks absolute http(s) URLs on one host, up to 50,000.
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UTM link builder
Add utm_source, utm_medium, utm_campaign and optional term, content and id tags to a URL, keeping its existing query and fragment.
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Hreflang tag generator
Build hreflang link tags from lines of language-region code and URL. Checks code format and absolute URLs, and flags a missing x-default.
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FAQ schema generator
Turn question and answer pairs into a FAQPage JSON-LD script tag with safe escaping. Use Q: and A: lines with a blank line between pairs.
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Punycode converter
Convert international domain names to Punycode (xn--) and back, label by label per RFC 3492, one domain per line. Lowercases labels; no full IDNA2008 mapping.
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Redirect rule generator
Turn "old-path new-url code" lines into redirect rules for _redirects (Netlify, Cloudflare Pages), Apache, nginx or JSON. Flags duplicates and loops.
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MIME type lookup
Look up the MIME type for file extensions or file names, or the extensions for a MIME type, one per line, from a built-in table of about 150 common types.
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