Diagnostic tools
Every check in one place. Filter by category or search by name.
DNS Lookup
Query any DNS record type for a domain.
A Lookup
Resolve IPv4 (A) records for a hostname.
AAAA Lookup
Resolve IPv6 (AAAA) records for a hostname.
MX Lookup
List mail exchangers and their priorities.
NS Lookup
List the authoritative name servers.
TXT Lookup
Read TXT records including SPF and verification tokens.
CNAME Lookup
Follow canonical name aliases.
SOA Lookup
Inspect the Start of Authority record.
SRV Lookup
Resolve service (SRV) records.
CAA Lookup
See which CAs may issue certificates.
PTR / Reverse DNS
Resolve an IP address back to a hostname.
SPF Lookup
Fetch and parse a domain's SPF record.
DKIM Lookup
Retrieve a DKIM public key by selector.
DMARC Lookup
Read and interpret a DMARC policy.
DMARC Generator
Build a valid DMARC record interactively.
BIMI Lookup
Check for a BIMI brand logo record.
MX Health
Score mail-server configuration and reachability.
SMTP Test
Connect to a mail server and read its banner.
Email Header Analyzer
Parse raw headers into a delivery timeline.
IP Lookup
Geolocation, ASN and network owner for an IP.
ASN Lookup
Look up an autonomous system number.
Ping
Measure round-trip latency to a host.
Open Port Scanner
Check common TCP ports on a host.
GeoIP Lookup
Approximate the location of an IP address.
SSL Checker
Validate a site's certificate and chain.
SSL Expiry Checker
Count the days left on a certificate.
Certificate Decoder
Decode a PEM certificate into readable fields.
WHOIS Lookup
Registration, registrar and nameserver details.
Domain Age
How long a domain has been registered.
Blacklist Check
Test an IP or domain against DNSBLs.
Domain Health Score
Aggregate DNS, email and SSL into one score.
HTTP Header Check
Inspect response headers for a URL.
Security Headers
Grade a site's HTTP security headers.
Website Availability
Check whether a site is up and how fast.
Robots.txt Checker
Fetch and summarise a site's robots.txt.
Base64 Encoder / Decoder
Encode or decode Base64 text instantly.
Hash Generator
Compute MD5, SHA-1 and SHA-256 digests.
URL Encoder / Decoder
Percent-encode or decode URL components.
JSON Formatter
Validate and pretty-print JSON.
Subnet Calculator
Compute network, broadcast and host ranges.
Password Generator
Create strong, random passwords.
Unix Timestamp Converter
Convert between Unix time and dates.