Query DNS records for any domain - A, AAAA, MX, TXT, NS, CNAME, SOA
Check mail server records for any domain with priority
Check if ports are open or closed on any server
Query domain registration and ownership info
Check SSL certificate details and validity
View HTTP response headers for any URL
Find hostname from IP address
Find your IP address and network details
Calculate IP ranges, subnets, and CIDR notation
Generate cron expressions with presets
Encode and decode Base64 strings
Generate MD5, SHA1, SHA256, SHA512 hashes
Validate and format JSON data
Generate secure random passwords
Encode and decode URL strings
Compare two texts and highlight differences
These free tools are great for quick checks. But for production systems, you need 24/7 automated monitoring with instant alerts.