Domain extension checker: one name across 52 extensions
In short: Type one name and check it across up to 52 extensions in five groups (popular, tech, business, brand and country), with each registry's answer: likely available, registered or unknown. Limit: Likely available isn't a guarantee: premium, reserved and blocked names can look free. The registrar confirms.
A domain extension checker tries one name across many extensions at once. Type a name such as northwindlabs, pick the groups (popular, tech, business, brand and shop, country) and each pairing comes back Likely available, Registered or Unknown from its registry's RDAP server and DNS. Up to 52 extensions per name; the registrar confirms price and eligibility.
Price: this tool is free. Checking a whole email list is from $9/mo, and the first 100 checks are free with Google, no card. See pricing
Sample result
acme-labs.app looks available; acme-labs.com is taken and acme-labs.io can't be confirmed.
- Name
- acme-labs
- .app
- Likely available
- .com
- Registered
What this means for you
See every extension of your name in one run, then confirm price and eligibility at a registrar.
- One name across five groups of extensions
- Brand and restricted TLDs left out
- No RDAP means unknown, never available
- 100 lookups a run, 500 when signed in
- RDAP
- TLDs
- Availability
By SimpleVerifier Team · Last updated
Also in: Português (Brasil) · Español · Deutsch · Français
Have a shortlist of full domains, or need more names?
- For a list of full domains on different extensions, paste it into the bulk domain availability checker: up to 100 a run, 500 signed in.
- Out of names? The available domain name generator builds them from keywords, and the domain hack generator puts the dot inside a word.
- Buying the domain to send email from? Check the addresses you'll send to before the first campaign: upload the CSV at /verify. The first 100 email checks are free with a Google sign-in, no card.
How do I check a domain name across all extensions?
- Type the name without an extension, such as northwindlabs. Typing northwindlabs.com works too; the extension is dropped. A few names, one per line, are each tried with every extension.
- Tick the groups to try. Popular and Tech are on by default (20 extensions); all five groups are 52.
- Press Check every extension. Results arrive 20 at a time as each registry answers, likely available first.
- Copy the likely available ones or download the CSV, then confirm the one you want at a registrar, which shows the price.
Example
- You enter
- The name
acme-labswith the Popular group ticked (10 extensions). - You get
acme-labs.comRegistered, with registrar and expiry where the registry shares them;acme-labs.appLikely available because Google Registry's RDAP server has no record and the name has no nameservers;acme-labs.ioUnknown, because the .io registry runs no RDAP and the name has no nameservers. Likely available first; copy them or download the CSV.- Limits
- Up to 100 name and extension pairs a run without an account and 500 when signed in with Google; up to 52 extensions per name.
How do I see if a domain name is available in every extension?
Type the name once and check it against each extension's registry. For every pairing, this checker finds the registry in IANA's RDAP bootstrap file, asks it for the domain as RFC 9224 describes, and checks whether the name has nameservers in DNS. No record and no nameservers means likely available.
The 52 extensions are grouped: Popular (.com, .net, .org, .co, .io, .ai, .app, .dev, .info, .biz), Tech, Business, Brand and shop, and Country (.us, .uk, .ca, .au, .de, .fr, .nl, .in, .eu, .ch). Every one takes registrations from the public; brand extensions such as .google and restricted ones such as .law are left out.
Why do some extensions show unknown?
Because their registry publishes no RDAP service. Several country codes, including .io, .co, .us, .de, .eu and .ch, aren't in IANA's RDAP bootstrap. For those, a name with nameservers is shown as registered, which DNS proves, and a name without them is unknown: it may be free, or registered but parked with no DNS.
A registry that is slow or rate-limiting also gives unknown. Run the name again a minute later, or check those extensions at a registrar.
Can anyone register a country-code extension?
Not always. Some country codes are open to anyone (.co, .io, .ai, .me), while others ask for a local presence: .ca for Canadian individuals and businesses, .au for an Australian connection, .eu for residents or organisations in the EU and EEA, and .us for people and organisations with a US nexus. This checker can't see eligibility, so read the registry's rules before you buy.
Should I buy the same name on several extensions?
If the name is your brand, the common choice is the .com plus the extensions people are most likely to type by mistake or that a competitor could use, such as your country code. Every extra domain is a renewal each year, so most businesses keep a short list and redirect the extras to the main site.
How is this different from a registrar's search?
| This checker | A registrar's search | |
|---|---|---|
| Source | Each registry's RDAP + DNS | The registrar's availability API |
| Prices | No | Yes |
| Registrar and expiry of taken names | Yes, where the registry shares them | Usually not |
| Extensions without RDAP | Unknown, never guessed | Covered if the registrar sells them |
| Suggestions it wants to sell | None | Often |
Who uses this tool, and for what?
- Founders
- See in one run whether the product name is free on .com, .io, .ai and the country code you sell in.
- Agencies
- Check a client's brand across the extensions worth registering defensively before the launch.
- Cold emailers
- Find which extensions of a brand are free for secondary sending domains.
- Domain investors
- See which extensions of a short name are taken, with registrar and expiry where the registry shares them.
What can’t this tool tell you?
- Likely available isn't a guarantee: premium, reserved and blocked names can look free. The registrar confirms.
- Extensions whose registry runs no RDAP, such as .io, .co, .us, .de, .eu and .ch, show unknown unless DNS proves the name is registered.
- It can't see eligibility rules; some country codes only register to residents or local businesses.
- No prices: RDAP doesn't publish them.
- 52 extensions, not all 1,400+: brand, restricted and rarely used extensions are left out.
Common questions
- How do I check all domain extensions for a name?
- Type the name here and pick the groups of extensions. Each one is checked against its registry's RDAP server and DNS, so you see which are likely available, registered or unknown in one run.
- Is this domain extension checker free?
- Yes. One name across all 52 extensions fits the 100 lookups a run without an account; after a free Google sign-in a run takes up to 500, so several names at once. No card.
- Does likely available mean I can register it?
- Usually, not always. Premium, reserved and blocked names can look free, and some country codes need a local presence. The registrar's checkout shows whether you can buy it and at what price.
- Which domain extension is best?
- .com is still the one people type by default. Beyond that, pick an extension that fits your audience: a country code for a local business, .io, .ai or .dev for a tech product. For sending email, any extension can be set up with SPF, DKIM and DMARC.
- Why isn't .io checked against a registry?
- The .io registry publishes no RDAP service in IANA's bootstrap, so there's no standard way to ask it. A .io name with nameservers shows as registered; one without shows unknown, never available.
- Can I check more than one name?
- Yes, one per line. Each name is tried with every extension you tick, and each pairing counts once toward the 100 a run (500 signed in).
Sources
Authentication and capacity are half of deliverability.
The other half is who you send to. Every hard bounce counts against the domain and inboxes you are sending from, and nothing in DNS can tell you which addresses on your list are dead.
- Bulk verification with real SMTP mailbox checks
- Hard bounces removed before a send, not discovered after
- Catch-all, disposable and role detection on every row
Plans from $9 a month, cancel anytime, no contract. Sign in with Google and your first 100 email checks are free, no card. The free tools stay free either way.