Language Code

GET/v0/language

Validates an ISO 639 language code in either the two-letter ISO 639-1 format (e.g. en) or the three-letter ISO 639-2 terminological format (e.g. eng). Covers all 184 ISO 639-1 languages. Input is case-insensitive. When valid, both the alpha-2 and alpha-3 codes are returned together with the English language name.

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Query Parameters

Parameter	Type	Required	Description
value	string	Yes	ISO 639-1 (2-letter) or ISO 639-2 (3-letter) language code, case-insensitive (e.g. `en`, `eng`, `PL`)

Example Requests

curl -H "Authorization: Bearer YOUR_API_KEY" \
  "https://api.isvalid.dev/v0/language?value=pl"

Response Fields

Field	Type	Description
valid	boolean	Whether the value is a recognised ISO 639 language code
format	string	Detected input format: `alpha-2` or `alpha-3`
alpha2	string \| null	ISO 639-1 two-letter code
alpha3	string	ISO 639-2 three-letter terminological code
name	string	English name of the language

Example Response

{
  "valid": true,
  "format": "alpha-2",
  "alpha2": "pl",
  "alpha3": "pol",
  "name": "Polish"
}

Example Response — invalid

{
  "valid": false
}

GET/v0/language/list

Returns the complete list of all 184 ISO 639-1 languages sorted alphabetically by English name.

Example Request

curl -H "Authorization: Bearer YOUR_API_KEY" \
  "https://api.isvalid.dev/v0/language/list"

Object Fields

Field	Type	Description
alpha2	string \| null	ISO 639-1 two-letter code
alpha3	string	ISO 639-2 three-letter terminological code
name	string	English name of the language

Example Response

[
  { "alpha2": "ab", "alpha3": "abk", "name": "Abkhazian" },
  { "alpha2": "aa", "alpha3": "aar", "name": "Afar" },
  { "alpha2": "af", "alpha3": "afr", "name": "Afrikaans" },
  ...
]