Free tools
Free network and SSL tools
Check SSL certificates and security headers, look up DNS, WHOIS and DNSSEC, test email setup and blacklists, measure website speed worldwide and more. Free, no sign-up.
SSL and security
SSL Checker
Check a site's certificate, chain, expiry and TLS versions.
Open toolSecurity Headers Checker
Grade a site's HTTP security headers from A+ to F.
Open toolCAA Record Generator
Choose which certificate authorities may issue for your domain.
Open toolSSL Tools
Generate CSRs, decode certificates, build chains, match keys.
Open toolCSR Generator
Create a certificate signing request and private key.
Open toolCertificate Decoder
Decode a PEM certificate: names, issuer, validity, key.
Open toolSSL Chain Builder
Fetch missing intermediates and build a full certificate chain.
Open toolCertificate Key Matcher
Check that a certificate and a private key belong together.
Open toolDNS and domains
DNS Lookup
Query A, AAAA, MX, TXT, NS, CAA and more from public resolvers.
Open toolWHOIS Lookup
Registrar, dates, status and nameservers of any domain.
Open toolDNS Propagation Checker
See what resolvers around the world return for your domain.
Open toolDNSSEC Checker
Validate a domain's DNSSEC chain: DS, DNSKEY and signatures.
Open toolPunycode Converter
Convert international domain names to and from xn-- form.
Open toolSubdomain Finder
Find a domain's subdomains in Certificate Transparency logs.
Open toolEmail DNS Checker
Check MX, SPF, DKIM, DMARC and BIMI in one go.
Open toolEmail Blacklist Check
Check an IP or mail domain against 15+ spam blacklists.
Open toolDMARC Generator
Build a DMARC record with policy, reports and alignment.
Open toolSPF Generator
Build an SPF record for your mail providers and servers.
Open toolWebsite and CDN
HTTP Headers Checker
See status codes, redirects and response headers of a URL.
Open toolWebsite Speed Test
Time to first byte and load time from 12 locations.
Open toolCDN Cache Checker
See which CDN serves a URL and whether it is cached worldwide.
Open toolIPv6 Test
Is a domain's website, DNS and mail reachable over IPv6?
Open toolIs It Down?
Check if a website is down for everyone or just you.
Open toolHTTP/2 and HTTP/3 Test
Check whether a site supports HTTP/2, HTTP/3 (QUIC) and TLS 1.3.
Open toolNetwork
What Is My IP
Your public IP address, reverse DNS and browser details.
Open toolPing and Traceroute
Ping, traceroute and MTR from probes worldwide.
Open toolSubnet Calculator
IPv4 and IPv6 CIDR: netmask, range, hosts.
Open toolPort Checker
Check whether a TCP port is open from the internet.
Open toolIP Lookup
Location, network (ASN) and reverse DNS of any IP address.
Open toolDeveloper tools
JWT Decoder
Decode a JSON Web Token's header, payload and expiry.
Open toolBase64 Encode / Decode
Encode and decode Base64 and URL-safe Base64 (UTF-8).
Open toolHash Generator
MD5, SHA-1, SHA-256, SHA-384 and SHA-512 of text or files.
Open toolPassword Generator
Strong random passwords and UUIDs, generated in your browser.
Open toolTimestamp Converter
Convert Unix timestamps to dates and back.
Open toolJSON Formatter
Format, validate, minify and sort JSON.
Open toolURL Encoder / Decoder
Percent-encode and decode URLs and query strings.
Open tool