Free tools
40 checks that run on the same engine as our API. No signup, no daily limit, and nothing you check is stored. They are free because they answer from numbering plans, public DNS and bundled reference data, which costs us nothing to serve.
Syntax, DNS, deliverability signals and the catch-all problem behind most false positives.
Free email address validator
Check syntax, DNS, MX records and deliverability signals for any email address. Free, no signup.
Disposable email address checker
Check whether an email address uses a throwaway or temporary inbox provider. Free, no signup.
Catch-all domain checker
Find out whether a domain accepts mail for every address - the reason email validators report false positives. Free.
Role account checker
Check whether an email address is a shared role mailbox like info@ or support@ rather than a person. Free.
Email typo checker and fixer
Catch misspelled email domains like gmial.com and get the correction. Free, no signup.
Email address normalizer
Reduce an address to its canonical form: strip plus tags, collapse Gmail dots, resolve provider aliases. Free, instant, no signup.
Email list deduplicator
Paste a list and find the duplicates plain matching misses — plus tags, Gmail dots, provider aliases and case. Free, runs on your input only.
Free email provider checker
Tell consumer mailboxes from company domains, and see why the distinction matters for signups, billing and lead scoring. Free.
Email syntax checker
Check an address against the rules that actually matter, and see which parts of the standard real mail servers ignore. Free and instant.
Phone
Numbering plans, regulator allocations and line types. All offline, all free.
Free phone number validator
Check whether a phone number is valid in its country numbering plan. Free, no signup, 200+ countries.
Reserved and fake phone number checker
Check whether a phone number sits in a regulator-reserved block that can never be allocated. Ofcom, ACMA, NANPA and more.
VoIP or mobile? Line type checker
Check whether a US phone number is likely VoIP rather than a real mobile. Free. The check cheap APIs get wrong 1 in 4 times.
E.164 phone number formatter
Convert any phone number into E.164 international format. Free, no signup, 200+ countries.
Phone number country lookup
Find which country and region a phone number belongs to, from the published numbering plan. Free, instant, no signup.
Toll-free number checker
Check whether a number is toll free, and what that means for sending SMS to it. Free, from the published numbering plan.
Premium rate number checker
Check whether a number is premium rate or shared cost before you dial or auto-dial it. Free, from the published numbering plan.
Bulk phone number cleaner
Paste a list of phone numbers and get them normalised to E.164, with the impossible ones separated out. Free, up to 1000 at a time.
Domain & DNS
Live DNS queries for mail routing and anti-spoofing configuration.
MX record lookup
Look up the MX records for any domain and see who handles its mail. Free, live DNS query, no signup.
SPF record checker
Check a domain SPF record for syntax problems, soft-fail settings and the 10-lookup limit. Free.
DMARC record checker
Check a domain DMARC policy, alignment and reporting setup. Free live DNS lookup, no signup.
DKIM record checker
Look up a DKIM public key by selector and check it is published correctly. Free, live DNS, no signup.
Domain age and registration checker
See when a domain was registered, by which registrar, and when it expires. Free, live registry lookup.
Email deliverability check
One check for MX, SPF, DMARC and DKIM on your sending domain, with what to fix first. Free, no signup.
BIMI record checker
Check whether a domain publishes a valid BIMI record, and whether it meets the DMARC requirement that has to come first. Free, live DNS.
MTA-STS checker
Check a domain MTA-STS policy: the DNS record, the hosted policy file, and whether the mode actually enforces TLS. Free and live.
DNSSEC checker
Check whether a domain is signed with DNSSEC and whether the chain of trust is complete. Free, live DNS, no signup.
CAA record lookup
See which certificate authorities are allowed to issue for a domain, and who gets notified if one tries. Free, live DNS.
Nameserver lookup
Find which nameservers are authoritative for a domain, who operates them, and whether they are spread across providers. Free and live.
TXT record lookup
List every TXT record on a domain and see what each one is for — SPF, DMARC, domain verification, and the ones nobody remembers adding. Free.
SPF lookup limit checker
Count the DNS lookups your SPF record costs, following every nested include. Over ten and SPF fails permanently. Free and live.
Email host lookup
Find out who actually handles mail for a domain — Google, Microsoft, a filtering layer, or their own servers. Free, from live MX records.
IP address
Range classification and network attribution, without a geolocation licence.
IP address checker
Check whether an IP address is public, private, reserved or carrier-grade NAT. Free, no signup, IPv4 and IPv6.
Datacenter IP checker
Check whether an IP belongs to a hosting provider such as AWS, Google Cloud or Hetzner rather than a home connection. Free.
Carrier-grade NAT (CGNAT) checker
Check whether an IP sits in the 100.64.0.0/10 carrier-grade NAT range shared between mobile subscribers. Free.
IP blacklist checker
Check an IP against the major public DNS blocklists that mail servers actually consult. Free, no signup.
Reverse DNS (PTR) lookup
Look up the PTR record for an IP and check it matches forward. Free, live DNS, no signup.
CIDR calculator
Work out the network, broadcast, usable range and host count for any IPv4 CIDR block. Free, instant, no signup.
IP in CIDR range checker
Check whether an IP address falls inside one or more CIDR blocks. Paste an allow-list and see which rule matched. Free.
ASN and network operator lookup
Find which network operator publishes the range containing an IP address. Built on operator-published ranges, so unclaimed addresses say so.
Bogon and private IP checker
Check whether an address is private, reserved, loopback or documentation-only — the addresses that should never appear as a public source. Free.
Where the free tools stop
Everything here is decidable offline or from public DNS: numbering plans, regulator allocations, MX records, SPF and DMARC, IP range tables. That covers a surprising amount of real-world bad data — misspelled domains, numbers that were never allocated, domains that publish an explicit refusal to accept mail.
What it cannot answer is whether a specific mailbox exists or whether a line is switched on right now. Those need a live conversation with a mail server or a carrier, which is what the paid API does — and where most of the industry quietly guesses instead.