About the Domain Availability Checker
The Domain Availability Checker takes a name and checks it against as many TLDs as you want — in parallel — using RDAP (Registration Data Access Protocol), the modern JSON-native replacement for WHOIS. Each TLD is queried against its authoritative registry through the rdap.org bootstrap service. Results come back in one or two seconds for a batch of 30.
Everything runs on our server (RDAP endpoints don't expose CORS for browser calls). Nothing is stored — the report is returned to your browser and forgotten.
How it works
For each requested TLD, the tool sends a concurrent GET to rdap.org/domain/<name>.<tld>. The response is interpreted as:
- Available (green) — HTTP 404, or a 200 body with an "errorCode" saying "not found".
- Taken (red) — HTTP 200 with domain data. The registrar name and expiry date are extracted when present.
- Unknown (amber) — RDAP server was rate-limited, timed out, or returned a non-standard response. Usually a retry succeeds.
Default TLD set
The default check covers 30 popular namespaces: com, net, org, io, ai, co, app, dev, me, xyz, tech, site, online, store, shop, cloud, info, biz, tv, ly, link, so, and the top ccTLDs us, uk, de, ca, in, fr, es, nl. Use the toggle chips to add or remove any, or type your own comma-separated list in the Custom field.
Accuracy caveats
RDAP is the authoritative source, so Taken results are 100% reliable. Available results are usually correct but can be overridden by:
- Premium names — the registry has marked the name as premium and priced it higher.
- Registry reserves — some names (short single-character strings, trademark blocks) are reserved.
- Recent deletions — a name that expired minutes ago may still be in the redemption grace period.
Always verify at the registrar before you commit — the price shown there is the final word.
Privacy & limits
Rate-limited to 15 checks per minute per IP. Each check queries up to 60 TLDs in parallel with concurrency 8. The upstream rdap.org service may keep logs — nothing this tool can control.