No account · capped runs per day

Free startup name and domain checker (2026)

This free startup domain checker takes a name and looks up nameserver records across the extensions founders actually use — .com, .io, .ai, .co, .app, .dev, .net — plus the get-, try- and use- variants. A registrar sets nameservers the moment a domain is registered, so parked and squatted names read as taken rather than free. No record at the registry means the domain is almost certainly available. It runs instantly, costs nothing, and we don't sell domains, so nothing here has an incentive to tell you your first choice is gone.

How the check works, and where it's wrong

We look up each candidate's nameserver (NS) records rather than its website. That distinction matters: a registrar delegates nameservers the moment a domain is registered, whether or not anything is ever published there. So a squatted domain with no site, and a parked domain showing ads, both read as taken — which is what you need to know.

  • NS records exist → taken. Registered, including parked and squatted.
  • No record at the registry → almost certainly free. Nobody has registered it.
  • Couldn't tell → a resolver timeout or an unusual answer. Re-run it.

The remaining gap is small but real: a domain sitting in a registrar's grace or redemption period, or registered and never delegated, can answer with nothing and show as free here. So use this to kill the obviously-taken names in seconds, then confirm the survivor at a registrar before you print anything.

Picking a name that doesn't cost you later

Naming advice is mostly aesthetics. These four are the ones that actually cost money when you get them wrong:

Say it out loud on a phone call. If a name needs spelling every single time, you will spell it every single time, forever, on every sales call and podcast. That is a real tax.

Check the trademark, not just the domain. A free .com means nothing if a company in your class already holds the mark. Search your national trademark register and the USPTO before you commit. This takes twenty minutes and prevents the most expensive rename there is.

Search the name plus your category. If page one is already an established company, you are volunteering to fight for your own name in search forever.

Don't buy the misspelling of a good name. Dropped vowels and creative spellings were a 2012 tactic born of .com scarcity. Now the alternative extensions are respectable, and a clean word on .io beats a mangled one on .com.

Which extension actually matters

.com is still the default a stranger types and the one that survives being read aloud badly. If it's available and affordable, take it.

.io and .ai carry no penalty with a technical or founder audience, and .ai has become the expected extension for AI products. Both are meaningfully more expensive to renew — check the renewal price, not the first-year price.

.co is the best fallback when the .com is a parked squat you won't pay for.

.app and .dev are on the HSTS preload list, which forces HTTPS. That's a small genuine security win and a signal to a developer audience.

The extension is not what makes a company work. Pick one in an afternoon, buy it, move on to the part that decides the outcome.

After you own the domain

A domain with nothing on it is a receipt, not an asset. The next move is a page that explains what you do and captures the people who care.

kitty.build generates that page from your validated idea — copy, structure, and a working capture form — publishes it to your own Cloudflare account, and points your domain at it. The domain, the DNS and the repo stay yours; export the whole thing any time. That's the part that turns a name into a test.

Questions

Is this domain checker free?
Yes, completely, with no account. We don't sell domains or take registrar commissions, so nothing here is nudging you toward a purchase.
Does 'probably free' mean I can definitely register it?
Almost always. It means the registry has no nameserver record for the domain, which covers nearly every unregistered name. The exceptions are domains in a grace or redemption period and ones registered but never delegated — so confirm at a registrar before you commit to the name.
Which domain extension should a startup use?
.com if you can get it clean, because it survives being read aloud. .io or .ai carry no penalty with a technical or AI-product audience but cost more to renew. .co is the best fallback. Check renewal pricing, not the first-year offer.
Do you check trademarks?
No, and no automated tool should claim to. Search your national register and the USPTO by hand for your goods and services class before committing. It takes twenty minutes and prevents the most expensive kind of rename.
Where do I register the domain?
Any registrar you like — we don't have a preferred one and earn nothing either way. If you plan to publish with kitty.build, a registrar that lets you change nameservers freely makes the Cloudflare setup one step.

Other free tools

Procedures that use it

One tool is a slice. Kitty is the whole run.

Nine specialist boards research your idea live and return a cited verdict. If it's worth building, the same engine builds and runs it — website, posts, ads, inbox — with nothing outbound sent until you say yes. Your first idea is free.

Feed her an idea

No card · No revenue share, ever · Your repo, your domain, your data