Verifying against the live site and live WHOIS/DNS…
Common questions
Is htmlvalidator.com legit or a scam?
AboutUs doesn't label sites "legit" or "a scam": this page lists the dated registration, DNS, HTTPS, mail-authentication and safety checks we could verify, each with its source, so you can decide for yourself.
Who owns htmlvalidator.com?
Nobody has completed AboutUs's owner verification for htmlvalidator.com. That's true of most sites here — it isn't itself a warning sign.
Correct a description, link or other detail. Submissions are reviewed before publication.
Lifeline · htmlvalidator.com over time
Checked in the last 30 daysOlder, dated recordFrom registration records
On AboutUs since 2006 · 2 registrar changes since Jul 3, 2011 · 5 ownership changes since 2007 · last checked Oct 25, 2026.
Registration
No registration date on file yet. AboutUs reads it from RDAP when the site is checked.
AboutUs record
AboutUs wiki pageAboutUs wiki pageJun 20, 2006 – Nov 9, 2013An AboutUs wiki page described htmlvalidator.com from Jun 20, 2006 to Nov 9, 2013 (3 edits).Source: AboutUs wiki archive, 2006–2023Said about itself in 2006Jul 1, 2006“AI Internet Solutions was established in 1997 to develop and market CSE HTML Validator, an award-winning, popular and powerful HTML, XHTML, CSS, link, spelling and accessibility checker for Windows. Since then, AI Inter…”Source: AboutUs wiki archive, 2006
Registrar
GoDaddy.com, LLCGoDaddy.com, LLCJul 3, 2011 – Jan 25, 2017Registrar GoDaddy.com, LLC (IANA 146) in the WHOIS and RDAP records held for htmlvalidator.com, from Jul 3, 2011 to Jan 25, 2017.Source: WHOIS / RDAP archive (who.is)NAMECHEAP INC
Ownership
Ownership recordsMay 24, 2007 – Jun 19, 2026Registration records for htmlvalidator.com are held from May 24, 2007 to Jun 19, 2026 (158 records). 5 changes of registrant name or organization are marked. Privacy-service and redaction changes are not counted.Source: WHOIS / RDAP archive (who.is); counted by registrant name and organization only
Zone file
Nameservers: tetrion.comNameservers: tetrion.comMay 24, 2007 – Oct 17, 2013Registration records listed tetrion.com nameservers (ns4.tetrion.com) for htmlvalidator.com from May 24, 2007 to Oct 17, 2013. Days a zone file covers are shown from the zone file instead.Source: From registration records (WHOIS / RDAP archive, who.is)
Certificate
AmazonAmazonDec 23, 2025 – Oct 29, 2026Amazon issued 1 certificate for htmlvalidator.com from Dec 23, 2025, the latest valid until Jan 20, 2027.Source: Certificate Transparency logs (AboutUs's own certificate-log reader)
2010201520202025Apr ’26← last 12 months, drawn wider
Every dated fact on this lifeline (23)
Jun 20, 2006 – Nov 9, 2013AboutUs record: An AboutUs wiki page described htmlvalidator.com from Jun 20, 2006 to Nov 9, 2013 (3 edits).Source: AboutUs wiki archive, 2006–2023
Jul 1, 2006AboutUs record: “AI Internet Solutions was established in 1997 to develop and market CSE HTML Validator, an award-winning, popular and powerful HTML, XHTML, CSS, link, spelling and accessibility checker for Windows. Since then, AI Inter…”Source: AboutUs wiki archive, 2006
May 24, 2007 – Jun 19, 2026Ownership: Registration records for htmlvalidator.com are held from May 24, 2007 to Jun 19, 2026 (158 records). 5 changes of registrant name or organization are marked. Privacy-service and redaction changes are not counted.Source: WHOIS / RDAP archive (who.is); counted by registrant name and organization only
May 24, 2007 – Oct 17, 2013Zone file: Registration records listed tetrion.com nameservers (ns4.tetrion.com) for htmlvalidator.com from May 24, 2007 to Oct 17, 2013. Days a zone file covers are shown from the zone file instead.Source: From registration records (WHOIS / RDAP archive, who.is)
Jul 3, 2011 – Jan 25, 2017Registrar: Registrar GoDaddy.com, LLC (IANA 146) in the WHOIS and RDAP records held for htmlvalidator.com, from Jul 3, 2011 to Jan 25, 2017.Source: WHOIS / RDAP archive (who.is)
Current AboutUs recordJun 23, 2026 – Aug 22, 2026 (latest)Authority and Safety last refreshed Aug 22, 2026.Source: AboutUs checks
Jul 12, 2018 – Jan 1, 2020
Registrar NAMECHEAP INC (IANA 1068) in the WHOIS and RDAP records held for htmlvalidator.com, from Jul 12, 2018 to Jan 1, 2020.
Source: WHOIS / RDAP archive (who.is)
NameSilo, LLCNameSilo, LLCApr 21, 2020 – Oct 25, 2026 (latest)Registrar NameSilo, LLC (IANA 1479) in the registration data recorded, first on Apr 21, 2020 and most recently on Oct 25, 2026.Source: RDAP, fetched Jun 23, 2026
Ownership change
Oct 20, 2013
The registrant name or organization in the registration record changed; first recorded Oct 20, 2013. Who it changed to is in the full report.
Source: WHOIS / RDAP archive (who.is); counted by registrant name and organization only
Ownership changeAug 10, 2025The registrant name or organization in the registration record changed; first recorded Aug 10, 2025. Who it changed to is in the full report.Source: WHOIS / RDAP archive (who.is); counted by registrant name and organization only
Ownership changeJan 11, 2026The registrant name or organization in the registration record changed; first recorded Jan 11, 2026. Who it changed to is in the full report.Source: WHOIS / RDAP archive (who.is); counted by registrant name and organization only
Ownership changeFeb 11, 2026The registrant name or organization in the registration record changed; first recorded Feb 11, 2026. Who it changed to is in the full report.Source: WHOIS / RDAP archive (who.is); counted by registrant name and organization only
Ownership changeFeb 23, 2026The registrant name or organization in the registration record changed; first recorded Feb 23, 2026. Who it changed to is in the full report.Source: WHOIS / RDAP archive (who.is); counted by registrant name and organization only
5 ownership changes, 2007–2026
Nameservers: tetrion.com
Nameservers: tetrion.comOct 18, 2013 – Apr 3, 2018tetrion.com (ns4.tetrion.com, ns6.tetrion.com) were the nameservers listed for htmlvalidator.com at every ICANN zone-file snapshot AboutUs holds from Oct 18, 2013 to Apr 3, 2018 (snapshots exist for only part of 2013–2018).Source: ICANN zone-file snapshots, 2013–2018 (legacy archive)
Nameservers: tetrion.comNameservers: tetrion.comApr 4, 2018 – Jun 9, 2022Registration records listed tetrion.com nameservers (ns4.tetrion.com) for htmlvalidator.com from Apr 4, 2018 to Jun 9, 2022. Days a zone file covers are shown from the zone file instead.Source: From registration records (WHOIS / RDAP archive, who.is)
Nameservers: linode.comAug 1, 2022 – Oct 7, 2025Registration records listed linode.com nameservers (ns1.linode.com, ns2.linode.com, ns3.linode.com…) for htmlvalidator.com from Aug 1, 2022 to Oct 7, 2025.Source: From registration records (WHOIS / RDAP archive, who.is)
DNS moved to linode.comAug 1, 2022htmlvalidator.com's nameservers moved from tetrion.com to linode.com at some point between Jun 9, 2022 and Aug 1, 2022. Last seen at tetrion.com: Jun 9, 2022 (registration record). First seen at linode.com: Aug 1, 2022 (registration record). AboutUs holds no nameserver records for the 53 days in between, so the date of the move is not known more closely.Source: Derived from the nameserver records on this lifeline (registration record → registration record)
Nameservers: CloudflareNov 8, 2025 – Jun 19, 2026Registration records listed Cloudflare nameservers (damon.ns.cloudflare.com, kayleigh.ns.cloudflare.com) for htmlvalidator.com from Nov 8, 2025 to Jun 19, 2026.Source: From registration records (WHOIS / RDAP archive, who.is)
DNS moved to CloudflareNov 8, 2025htmlvalidator.com's nameservers moved from linode.com to Cloudflare between Oct 7, 2025 and Nov 8, 2025. Last seen at linode.com: Oct 7, 2025 (registration record). First seen at Cloudflare: Nov 8, 2025 (registration record).Source: Derived from the nameserver records on this lifeline (registration record → registration record)
Seen in the .com zone fileSep 8, 2026 – Oct 23, 2026 (latest)First seen in the .com zone file records AboutUs holds on Sep 8, 2026; latest sighting Oct 23, 2026. Nameservers on Oct 23, 2026: damon.ns.cloudflare.com, kayleigh.ns.cloudflare.com.Source: ICANN CZDS zone file, snapshot Oct 23, 2026
Google Trust Services
Apr 17, 2026 – Oct 29, 2026 (latest)
Google Trust Services issued 4 certificates for htmlvalidator.com from Apr 17, 2026, the latest valid until Jan 9, 2027. Seen in use on Oct 25, 2026.
Source: Certificate Transparency logs (AboutUs's own certificate-log reader); TLS check, Oct 25, 2026
Let's EncryptMay 3, 2026 – Oct 29, 2026Let's Encrypt issued 6 certificates for htmlvalidator.com from May 3, 2026, the latest valid until Jan 14, 2027.Source: Certificate Transparency logs (AboutUs's own certificate-log reader)
Oct 18, 2013 – Apr 3, 2018Zone file: tetrion.com (ns4.tetrion.com, ns6.tetrion.com) were the nameservers listed for htmlvalidator.com at every ICANN zone-file snapshot AboutUs holds from Oct 18, 2013 to Apr 3, 2018 (snapshots exist for only part of 2013–2018).Source: ICANN zone-file snapshots, 2013–2018 (legacy archive)
Oct 20, 2013Ownership: The registrant name or organization in the registration record changed; first recorded Oct 20, 2013. Who it changed to is in the full report.Source: WHOIS / RDAP archive (who.is); counted by registrant name and organization only
Apr 4, 2018 – Jun 9, 2022Zone file: Registration records listed tetrion.com nameservers (ns4.tetrion.com) for htmlvalidator.com from Apr 4, 2018 to Jun 9, 2022. Days a zone file covers are shown from the zone file instead.Source: From registration records (WHOIS / RDAP archive, who.is)
Jul 12, 2018 – Jan 1, 2020Registrar: Registrar NAMECHEAP INC (IANA 1068) in the WHOIS and RDAP records held for htmlvalidator.com, from Jul 12, 2018 to Jan 1, 2020.Source: WHOIS / RDAP archive (who.is)
Apr 21, 2020 – Oct 25, 2026Registrar: Registrar NameSilo, LLC (IANA 1479) in the registration data recorded, first on Apr 21, 2020 and most recently on Oct 25, 2026.Source: RDAP, fetched Jun 23, 2026
Aug 1, 2022 – Oct 7, 2025Zone file: Registration records listed linode.com nameservers (ns1.linode.com, ns2.linode.com, ns3.linode.com…) for htmlvalidator.com from Aug 1, 2022 to Oct 7, 2025.Source: From registration records (WHOIS / RDAP archive, who.is)
Aug 1, 2022Zone file: htmlvalidator.com's nameservers moved from tetrion.com to linode.com at some point between Jun 9, 2022 and Aug 1, 2022. Last seen at tetrion.com: Jun 9, 2022 (registration record). First seen at linode.com: Aug 1, 2022 (registration record). AboutUs holds no nameserver records for the 53 days in between, so the date of the move is not known more closely.Source: Derived from the nameserver records on this lifeline (registration record → registration record)
Aug 10, 2025Ownership: The registrant name or organization in the registration record changed; first recorded Aug 10, 2025. Who it changed to is in the full report.Source: WHOIS / RDAP archive (who.is); counted by registrant name and organization only
Nov 8, 2025 – Jun 19, 2026Zone file: Registration records listed Cloudflare nameservers (damon.ns.cloudflare.com, kayleigh.ns.cloudflare.com) for htmlvalidator.com from Nov 8, 2025 to Jun 19, 2026.Source: From registration records (WHOIS / RDAP archive, who.is)
Nov 8, 2025Zone file: htmlvalidator.com's nameservers moved from linode.com to Cloudflare between Oct 7, 2025 and Nov 8, 2025. Last seen at linode.com: Oct 7, 2025 (registration record). First seen at Cloudflare: Nov 8, 2025 (registration record).Source: Derived from the nameserver records on this lifeline (registration record → registration record)
Dec 23, 2025 – Oct 29, 2026Certificate: Amazon issued 1 certificate for htmlvalidator.com from Dec 23, 2025, the latest valid until Jan 20, 2027.Source: Certificate Transparency logs (AboutUs's own certificate-log reader)
Jan 11, 2026Ownership: The registrant name or organization in the registration record changed; first recorded Jan 11, 2026. Who it changed to is in the full report.Source: WHOIS / RDAP archive (who.is); counted by registrant name and organization only
Feb 11, 2026Ownership: The registrant name or organization in the registration record changed; first recorded Feb 11, 2026. Who it changed to is in the full report.Source: WHOIS / RDAP archive (who.is); counted by registrant name and organization only
Feb 23, 2026Ownership: The registrant name or organization in the registration record changed; first recorded Feb 23, 2026. Who it changed to is in the full report.Source: WHOIS / RDAP archive (who.is); counted by registrant name and organization only
Apr 17, 2026 – Oct 29, 2026Certificate: Google Trust Services issued 4 certificates for htmlvalidator.com from Apr 17, 2026, the latest valid until Jan 9, 2027. Seen in use on Oct 25, 2026.Source: Certificate Transparency logs (AboutUs's own certificate-log reader); TLS check, Oct 25, 2026
May 3, 2026 – Oct 29, 2026Certificate: Let's Encrypt issued 6 certificates for htmlvalidator.com from May 3, 2026, the latest valid until Jan 14, 2027.Source: Certificate Transparency logs (AboutUs's own certificate-log reader)
Jun 23, 2026 – Aug 22, 2026AboutUs record: Authority and Safety last refreshed Aug 22, 2026.Source: AboutUs checks
Sep 8, 2026 – Oct 23, 2026Zone file: First seen in the .com zone file records AboutUs holds on Sep 8, 2026; latest sighting Oct 23, 2026. Nameservers on Oct 23, 2026: damon.ns.cloudflare.com, kayleigh.ns.cloudflare.com.Source: ICANN CZDS zone file, snapshot Oct 23, 2026
The site's bot protection blocked AboutUs's HTTPS check; all 1 of the other checks passed (Oct 29, 2026).
Registered 1997 · AboutUs's live check was blocked by the site's bot protection
HtmlValidatOr.com Provides easy to use offline HTML, XHTML, and CSS.
About AI Internet Solutions AI Internet Solutions was established in 1997 to develop and market CSE HTML Validator, an award-winning, popular and powerful HTML, XHTML, CSS, link, spelling and accessibility checker for Windows.
AboutUs has not vetted this site. Everything below is what we could measure automatically. Anything you do on the site — paying, sharing personal details, downloading — is between you and the site, not AboutUs.
Current facts
Latest available measurements; dated entries retain their dates. These are measurements, not an endorsement of the site.
latest result
Domain registered Jan 15, 1997 — 29 years old.
latest result
Registrar on record: NameSilo, LLC — unchanged since AboutUs began tracking (Sep 26, 2026).
checked Sep 30, 2026
The live front page reads as a software or technology site that sells software or a subscription, mainly for specialists in its field.
Authority 50/100— ahead of 50% of the August 2026 scored sampleClear
Why this authority score
50 is a percentile: higher than 50% of sites we score.
How it's calculated
Prominence (Tranco rank #328,400)+5
Verified continuity: 29.8 years (RDAP registration)+11
Security & email hygiene+3
Calibration adjustment (published map)+8
Model score: 27/99 — what these reason lines add up to.
Published Authority (percentile): 50/100 — this site's rank against the August 2026 scored sample. Public Authority is capped at 99.
Safety evidence
No unexpired threat-feed result; name-similarity check available (recorded about 67 days ago); 3/3 transport and email checks available (oldest recorded about 67 days ago). This is evidence coverage, not a probability that a website is safe.
No caution flags in the available scoring observations; this is not a complete safety assessment
What htmlvalidator.com said about itself, 2006
Quoted from the site's AboutUs wiki page in each year it changed (1 version). These are the page's own words at the time, not AboutUs's assessment. New words · dropped words
2006
AI Internet Solutions was established in 1997 to develop and market CSE HTML Validator, an award-winning, popular and powerful HTML, XHTML, CSS, link, spelling and accessibility checker for Windows. Since then, AI Internet Solutions has remained a customer focused business with great customer service and great products such as CSE HTML Validator in multiple editions.
Site history
Dated record — historical facts always carry their date.
1997
Domain registered (Jan 15, 1997).
2026
Checked today — The site's bot protection blocked AboutUs's HTTPS check; all 1 of the other checks passed (Oct 29, 2026).
✓ domain continuity 29 years registered– live check blocked the site's bot protection turned the check away Oct 29, 2026