NetDetectHub

NetDetectHub is a free set of network tools where every result starts with one plain-English sentence, then shows the raw data. Check your IP and WebRTC leaks, look up DNS records and propagation, WHOIS, MX, SPF, DKIM and DMARC (with a corrected record to paste), test if a site is down, check SSL certificates, HTTP headers and redirects, and calculate subnets. No sign-up and nothing you check is stored.