404 Checker
404 Checker
Essential Tools for Website Health & Performance
Fast, real-time utilities to inspect HTTP response codes, trace redirect chains, audit raw headers, test SEO directives, verify SSL security, and debug DNS records.
The 404 Checker
HTTP Status Code Validator
Check the exact HTTP status code (200, 301, 404, 500) returned by any URL, image, or document to ensure your server and error pages respond correctly.
Full Header Checker
Raw Response & Security Headers
Inspect all HTTP response headers including security policies (CSP, HSTS), cache headers, server software, compression, and cookies.
Redirect Chain Analyser
Trace Hops, 301/302 & Loops
Trace every hop a URL makes before its final destination. Detect multi-hop chains, redirect loops, and slow canonical routes.
Broken Link Checker
Page Link Auditor
Crawl all internal and external links on a webpage to automatically identify broken URLs, 404 dead ends, and bad anchors.
Robots.txt & Sitemap
Crawl Directives & XML Sitemaps
Parse robots.txt rules, check for crawler blocking (Disallow /), inspect sitemap declarations, and detect bot challenge pages.
SSL Certificate Checker
Certificate & HTTPS Health
Verify SSL/TLS certificate validity, expiry countdown, issuing CA authority, SAN domains, and TLS protocol security.
DNS Record Lookup
Query A, AAAA, MX, CNAME & TXT
Query live DNS records across authoritative nameservers for any domain name with full TTL and IP geolocation data.
Social Card Previewer
Open Graph & Twitter / X Cards
Preview how your web pages look when shared across Twitter/X, Facebook, LinkedIn, Discord, and Slack with tag diagnostics.
Need HTTP Status Code & Header Documentation?
Explore our reference guides for comprehensive definitions, standard RFC status code categories, and server configuration tips.