Website Status &
Security Toolkit
Professional-grade diagnostics for developers and website owners. Check uptime via real HTTP + TCP + DNS checks, inspect live SSL certificates, query DNS records, and analyze HTTP security headers.
Four Diagnostic Tools, One Interface
Server-Side Checks, Not Browser Hacks
You Submit a Domain
Enter any domain — with or without www or https://. We normalize it automatically.
Server Runs the Check
Our Node.js servers query DNS resolvers, open TCP connections, perform TLS handshakes, and send HTTP requests directly. No third-party APIs.
Results Are Cached
Results cache for 5 minutes (2 min for uptime). Cached results are clearly labeled. Rate limiting prevents abuse.
Share the Result URL
Every check has a permanent shareable URL (e.g. /ssl-check/github.com) that also ranks in search engines.
Understand What You're Checking
What is DNS?
The Domain Name System translates human-readable domains into IP addresses. It's hierarchical and distributed — changes take time to propagate globally because resolvers cache records according to their TTL values. A, MX, NS, TXT, and CNAME records each serve distinct routing and verification purposes.
What is SSL/TLS?
TLS encrypts data in transit and authenticates server identity. Certificates are issued by Certificate Authorities and expire — an expired certificate blocks most users instantly. This toolkit checks certificates via a real TLS handshake, not a third-party log, giving you exactly what visitors see.
Website Uptime Explained
True uptime requires three checks: DNS resolution (does the domain resolve?), TCP connectivity (is port 443 open?), and HTTP response (does the server return 2xx/3xx?). DNS resolving alone does not mean your site is up — the application could still return 500 errors.
HTTP Security Headers
Security headers tell browsers how to handle your content — blocking XSS, clickjacking, and protocol downgrade attacks. Key headers include Strict-Transport-Security, Content-Security-Policy, X-Frame-Options, and X-Content-Type-Options. Most require only server config changes, not code changes.
In-Depth Guides for Developers
Is It Down for Everyone or Just Me?
How to conclusively check if a site is globally down, troubleshoot DNS issues, and understand HTTP status codes.
Read article →Complete Guide to DNS Lookup
Every DNS record type explained: A, AAAA, MX, NS, TXT, CNAME, SOA. Includes propagation and troubleshooting.
Read article →SSL Certificate Checker Guide
How to inspect SSL certs, fix common errors, set up auto-renewal, and implement HSTS.
Read article →HTTP Security Headers Guide
Implement HSTS, CSP, X-Frame-Options and all critical security headers with Nginx and Apache examples.
Read article →No Third-Party APIs
All checks run directly from our servers. No Google DNS or crt.sh dependencies that can fail or impose rate limits.
Smart Caching
Results cache for 5 minutes with Redis. In-memory fallback ensures availability even without Redis.
Shareable URLs
Every check generates a permanent URL that works for sharing, bookmarking, and ranking in search engines.
Open Architecture
Server-side Next.js API routes. Add Redis, swap caching strategies, or extend with new tools.