DNS, email, certificate and network diagnostics. Always free: no ads, no cookies, no account.

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DNS

Check Domain
DNS Records
DNS Propagation
DNSSEC Checker
CAA Records
Bulk Reverse DNS
WHOIS Lookup

Email

Email Health Check
SPF Validator
DMARC Checker
MTA-STS & TLS-RPT
BIMI Checker
Email Validator
SPF Generator
DKIM Generator
DMARC Generator

HTTP

Check Website
HTTP Headers
SSL Checker
Meta Tags & Open Graph
robots.txt Checker
security.txt Checker
TLS Versions
Certificate Decoder
Certificate Chain

Network

Port & Latency
Blacklist Check

Utilities

Subnet Calculator
Base64
Punycode
JWT Decoder
Hash Generator
UUID Generator
Password Generator
Timestamp Converter
URL Encoder
JSON & YAML
Cron Checker
What Is My IP

Subnet Calculator

Subnet calculator

Address or CIDR block: IPv4 or IPv6. Without a prefix, a single host is assumed.

Built by @isholgueras

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