Free web and network diagnostic tools for developers, sysadmins, and SEO professionals. DNS Checker queries authoritative nameservers to verify DNS propagation across global regions. IP Lookup returns geolocation, ASN, and hosting provider data for any IP address. HTTP Headers Inspector fetches the full response headers for any URL - useful for verifying caching, compression, redirects, and security headers. Open Graph Preview shows how a URL will appear when shared on social media. SSL/TLS Reference documents protocol versions and certificate types. Port Reference documents common ports and their protocols. URL Parser, HAR Viewer, HTTP Simulator, and WebSocket Tester round out the developer debugging toolkit.

When to use Network & Web

1After updating DNS records: use DNS Checker to verify propagation across multiple global nameservers without waiting for caches to clear.
2Diagnosing site performance: use HTTP Headers Inspector to confirm that Cache-Control, Content-Encoding (gzip/brotli), and CDN headers are correctly set.
3Social sharing issues: use Open Graph Preview to see exactly how your page appears on Facebook, LinkedIn, Twitter, and WhatsApp before publishing.
4Security audits: check response headers for HSTS, Content-Security-Policy, X-Frame-Options, and other security headers using the HTTP Headers tool.
5API development: use the HTTP Simulator to send test requests and inspect full responses, or the WebSocket Tester to debug real-time connection issues.

Frequently Asked Questions

How do I check if my DNS has propagated?+

Use the DNS Checker tool. Enter your domain and select the record type (A, AAAA, CNAME, MX, TXT, NS). The tool queries multiple authoritative resolvers across different geographic regions and shows which ones have picked up the new record - helping you confirm global propagation.

What does a CDN response header look like?+

CDN responses typically include headers like CF-Cache-Status: HIT (Cloudflare), X-Cache: Hit from cloudfront (CloudFront), or Age: 3600 (time the response has been cached). The HTTP Headers tool displays all response headers so you can verify your CDN is serving cached responses correctly.

Why does my Open Graph image not show when sharing?+

Common causes: the og:image URL is returning 404, the image is smaller than 200×200px, the server is blocking the social crawler's user agent, or the page requires JavaScript to render the OG tags (social crawlers don't execute JS). Use the Open Graph Preview tool to fetch and display the current OG tags for your URL.

What is a HAR file and how do I use it?+

A HAR (HTTP Archive) file is an export of all network requests made during a browser session, captured from DevTools. It includes request/response headers, payloads, status codes, and timing data. Upload a HAR file to the HAR Viewer to analyse page load performance, identify slow requests, and inspect API responses.

About Network & Web

When to use Network & Web

1After updating DNS records: use DNS Checker to verify propagation across multiple global nameservers without waiting for caches to clear.

2Diagnosing site performance: use HTTP Headers Inspector to confirm that Cache-Control, Content-Encoding (gzip/brotli), and CDN headers are correctly set.

3Social sharing issues: use Open Graph Preview to see exactly how your page appears on Facebook, LinkedIn, Twitter, and WhatsApp before publishing.

4Security audits: check response headers for HSTS, Content-Security-Policy, X-Frame-Options, and other security headers using the HTTP Headers tool.

5API development: use the HTTP Simulator to send test requests and inspect full responses, or the WebSocket Tester to debug real-time connection issues.

Frequently Asked Questions

How do I check if my DNS has propagated?+

What does a CDN response header look like?+

Why does my Open Graph image not show when sharing?+

What is a HAR file and how do I use it?+