Which country owns a domain extension? (.io, .ai, .tv)

Every two-letter domain ending is a country-code top-level domain (ccTLD) assigned to a specific country or territory. The "tech" favourites are just borrowed: .io is the British Indian Ocean Territory, .ai is Anguilla, .tv is Tuvalu, .co is Colombia, .me is Montenegro.

TLD → country

Pass a domain ending (the leading dot is optional) and get the country that owns it:

curl https://countries.dev/tld/io

[
  {
    "name": "British Indian Ocean Territory",
    "alpha2Code": "IO",
    "flag": "🇮🇴",
    "topLevelDomain": [".io"],
    "callingCodes": ["246"]
  }
]

It returns an array because a handful of TLDs map to more than one entry.

Country → TLD

Going the other way, a country's domains live on its record:

curl https://countries.dev/alpha/CO

{ "name": "Colombia", "alpha2Code": "CO", "topLevelDomain": [".co"] }

One gotcha

Generic TLDs like .com, .org and .dev aren't owned by a country, so they won't match — only ccTLDs resolve. If you're validating user input, treat a 404 as "not a country domain".

Top-level domain docs →