{"slug":"domain-availability-checker-underscoredone-com-check-bf1113","title":"Give this API up to 10 domain names and it tells you whether each has a registra","host":"domain-availability-checker.underscoredone.com","method":"POST","resource":"https://domain-availability-checker.underscoredone.com/check","category":"company","description":"Give this API up to 10 domain names and it tells you whether each has a registration record at the official registry. It uses RDAP, the structured replacement for WHOIS, so there is no free-text parsing. Each domain comes back as 'registered', 'unregistered', or 'indeterminate' when the registry has","price_listed":0.01,"price_asked":0.01,"state":"answering","state_label":"Answering","checks_7d":1,"answered_7d":1,"latency_ms_median":828,"reported_calls_30d":3,"reported_payers_30d":3,"networks":["eip155:8453","solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp"],"badge":"unverified","paid_checks_7d":0,"paid_ok_7d":0,"example_input":{"body":{"domains":["example.com","mybrand.ai","coolstartup.io"]},"bodyType":"json","method":"POST","type":"http"},"output_schema":{"$schema":"https://json-schema.org/draft/2020-12/schema","properties":{"input":{"additionalProperties":false,"properties":{"body":{"additionalProperties":false,"properties":{"domains":{"description":"Between 1 and 10 domain names to check, like 'example.com' or 'mybrand.ai'. Use the plain registrable domain only — no 'https://', no 'www.', no subdomains.","type":"array"}},"required":["domains"],"type":"object"},"bodyType":{"enum":["json","form-data","text"],"type":"string"},"method":{"enum":["POST","PUT","PATCH"],"type":"string"},"type":{"const":"http","type":"string"}},"required":["type","method","bodyType","body"],"type":"object"},"output":{"properties":{"example":{"properties":{"api_version":{"type":"string"},"count":{"type":"integer"},"disclaimer":{"type":"string"},"queried_at":{"type":"string"},"results":{"items":{"type":"object"},"type":"array"}},"required":["count","results","queried_at","disclaimer","api_version"],"type":"object"},"type":{"type":"string"}},"required":["type"],"type":"object"}},"required":["input"],"type":"object"},"history":[{"day":"2026-09-24","reachable":true,"status":402,"valid_402":true,"asked_usdc":0.01,"price_match":true,"latency_ms":828,"error":null}],"description_full":"Give this API up to 10 domain names and it tells you whether each has a registration record at the official registry. It uses RDAP, the structured replacement for WHOIS, so there is no free-text parsing. Each domain comes back as 'registered', 'unregistered', or 'indeterminate' when the registry has no RDAP for that ending. 'Unregistered' means no record was found, which usually means available - but reserved and premium names also return no record. Registration status only; no pricing.","last_updated":"2026-09-14T19:48:34.787Z","schemes":["exact"]}