Tools / Domain checker
Domain checker
How to read the results
Most domain checkers say "available" when they only know a name does not resolve. This one asks the registry that owns each TLD, then a registrar, and tells you how sure it is.
- Available
- Not registered at the registry, and a registrar confirms it can be bought at the standard price. The only answer safe to plan around.
- Premium
- Not registered, but sold at a premium price. Short and common names are often premium.
- Not available
- Not registered, but reserved or held back, so it cannot be bought at the standard price. A registry shows these as free; a registrar lists them as taken.
- Unconfirmed
- The registry shows no registration, but nothing confirmed it can be bought. Reserved and premium names look the same here, so check at a registrar.
- Taken
- Someone holds it. A name in its deletion period is marked, because it may become free soon.
- Closed TLDs
- Brand and restricted TLDs are hidden by default. A name there can show as free and still not be something you can register.
Registries and registrars limit how often they can be asked, so the long tail of TLDs is checked in the order people look for them, and some answers stay unconfirmed. The page says which is which.
API and MCP server
The same checker, for scripts and AI agents. No key, 20 names a day per address. One name is one check, however many TLDs. Results carry the same honest states as this page.
REST
curl "https://privatebyte.com/api/public/tools/domain?name=acme&tlds=popular&only=available"MCP (remote, Streamable HTTP). Add it to Claude Code:
claude mcp add --transport http privatebyte-domains https://privatebyte.com/api/public/tools/mcpOr add it to any MCP client’s configuration:
{ "mcpServers": { "privatebyte-domains": { "type": "http", "url": "https://privatebyte.com/api/public/tools/mcp" } } }The server has one tool, check_domain. Arguments: name (required), tlds (popular, open, all or a list), only (one state) and include_closed.
Questions
How does the domain checker work?
It asks each TLD's own registry whether the name is registered, using RDAP where the registry offers it and WHOIS for popular TLDs that do not, such as .io, .co and .de. Names the registry says are unregistered are then confirmed with a registrar, because registries also answer "not registered" for reserved and premium names. If something cannot be confirmed, it says so. Results appear as each registry answers, so the popular TLDs show up in about a second.
Why does it say "unconfirmed" instead of "available"?
A registry answers "not registered" for names it holds back, such as reserved and premium names, which a registrar then lists as taken or sells at a high price. DNS has the same blind spot. We only say "available" when both the registry and a registrar agree, and mark everything else as unconfirmed.
Does it show prices or let me register?
No. We show whether a name is available, premium or reserved, but not prices: those are set by the registrar you buy from, so confirm the price there.
How many TLDs does it check?
Popular covers about fifty. All open covers about six hundred TLDs and suffixes that registrars sell to the public, including co.uk and com.au. Every TLD adds the rest of the root zone, about fifteen hundred in all, including closed brand TLDs that are hidden by default because you cannot register a name there.
Why are some results unconfirmed or missing?
Registries limit how often they can be asked, and we respect that. A registry that asks us to slow down is left alone until it says we can resume, and its TLDs fall back to DNS. Popular TLDs are always checked first.
Got the name? Point it at a PrivateByte server with a dedicated IPv4 and reverse DNS you control.