How to Check Many Domain Names at Once (Bulk Availability Check)

To check many domain names at once, paste the list into the bulk domain availability checker. It asks each name's TLD registry over RDAP and checks DNS for nameservers, then labels every name Likely available, Registered or Unknown. You can check up to 100 names a run, or 500 after a free Google sign-in, and download the result as CSV.

Check a list of domain names now →

Check many domains with the bulk checker

1. Open the bulk domain availability checker.
2. Paste the names, one per line. Full names like acme-mail.com are checked as written. Bare names like acmehq are tried with every TLD you tick (.com by default), and each pairing counts toward the limit.
3. Press Check availability. Results arrive in batches of 20 as each registry answers.
4. Read each status: Likely available, Registered (with registrar and expiry date where the registry shares them) or Unknown.
5. Tick Show only likely available, download the CSV, and confirm the names you want at a registrar, which also shows the price.

More than 500 names? Split the list into runs of 500 and download the CSV after each.

Check domains manually with RDAP or whois

RDAP is the protocol ICANN describes as "the replacement for the WHOIS protocol" (ICANN RDAP page, read 8 November 2026). Each TLD's RDAP server is listed in IANA's bootstrap file; for .com it is https://rdap.verisign.com/com/v1/.

# A 404 means the registry has no record of the name; JSON means it's registered
curl -s -o /dev/null -w "%{http_code}\n" https://rdap.verisign.com/com/v1/domain/acme-mail.com

# Loop over a file of .com names, one per line
while read d; do
  echo "$d $(curl -s -o /dev/null -w '%{http_code}' https://rdap.verisign.com/com/v1/domain/$d)"
done < domains.txt

The classic whois acme-mail.com works too, but each TLD formats its answer differently, and many registries rate-limit repeated queries, so a long list is slow by hand. The loop above only works for one TLD at a time, because each TLD has its own RDAP server.

Why some results are unknown

Several country-code TLDs, including .io, .co and .de, don't appear in IANA's RDAP bootstrap file (checked 8 November 2026), so there's no standard way to ask their registries. 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 without DNS. A slow or rate-limiting registry also gives Unknown; run those names again a minute later. Unknown is never shown as available.

When a taken domain comes back

Not on its expiry date. Under ICANN's Expired Registration Recovery Policy (read 8 November 2026), gTLD registries offer a "Redemption Grace Period ("RGP") of 30 days immediately following the deletion of a registration", during which the previous owner can still restore it. Many expired names are renewed or auctioned before that. The bulk domain expiry checker shows when each registered name on your list expires.

Buying domains for cold email?

Naming advice is in naming cold email domains, and setup in cold email domain setup. A new domain's reputation is fragile: hard bounces in the first campaigns count against it first. Check the list you'll send to before the first send.

Next step: check the list you'll send to

Upload your CSV at /verify. Each address gets a live mailbox check without sending a message, and you can export valid, risky and invalid rows separately. The first 100 checks are free with a Google sign-in, no card.

Pro, $39 a month: Unlimited email verification.* Never metered, never cut off. Starter is $9 a month for 2,500 checks. See pricing.

*Fair use: the first 100,000 checks a month at full speed, then slower, never cut off.