json schema for langtags.json (https://github.com/silnrsi/langtags/blob/master/doc/langtags.md)

langtags.schema.json

{
  "$schema": "http://json-schema.org/schema#",
  "$ref": "#/definitions/langtags",
  "definitions": {
    "langtags": {
      "type": "array",
      "items": { "oneOf": [
        {"$ref": "#/definitions/langtag"},
        {"$ref": "#/definitions/_globalvar"},
        {"$ref": "#/definitions/_phonvar"},
        {"$ref": "#/definitions/_version"}
      ] },
      "additionalItems": false
    },

    "langtag": {
      "type": "object",
      "properties": {
        "tag": {
          "$ref": "#/definitions/bcp47"
        },
        "full": {
          "type": "string"
        },
        "tags": {
          "type": "array",
          "items": { "$ref": "#/definitions/bcp47" },
          "additionalItems": false
        },
        "variants": {
          "type": "array",
          "items": { "$ref": "#/definitions/bcp47_variant" },
          "additionalItems": false
        },
        "iso639_3": {
          "$ref": "#/definitions/iso639_3"
        },
        "region": {
          "$ref": "#/definitions/iso3166_1"
        },
        "regions": {
          "type": "array",
          "items": { "$ref": "#/definitions/iso3166_1" },
          "additionalItems": false
        },
        "regionname": {
          "type": "string"
        },
        "iana": {
          "oneOf": [
            { "type": "string" },
            { "type": "array", "items": {"type":"string"} }
          ]
        },
        "name": {
          "type": "string"
        },
        "names": {
          "type": "array",
          "items": { "type": "string" }
        },
        "localname": {
          "type": "string"
        },
        "sldr": {
          "type": "boolean"
        },
        "nophonvars": {
          "type": "boolean"
        },
        "script": {
          "$ref": "#/definitions/iso15924"
        },
        "localnames": {
          "type": "array",
          "items": { "type": "string" }
        },
        "latnnames": {
          "type": "array",
          "items": { "type": "string" }
        },
        "suppress": {
          "type": "boolean"
        },
        "windows": {
          "$ref": "#/definitions/bcp47"
        },
        "rod": { "type": "string"}
      },
      "required": ["full"],
      "additionalProperties": false
    },

    "_globalvar": {
      "type": "object",
      "properties": {
        "tag": {
          "type": "string",
          "const": "_globalvar"
        },
        "variants": {
          "type": "array",
          "items": { "type": "string" },
          "additionalItems": false
        }
      },
      "required": ["tag", "variants"],
      "additionalProperties": false
    },

    "_phonvar": {
      "type": "object",
      "properties": {
        "tag": {
          "type": "string",
          "const": "_phonvar"
        },
        "variants": {
          "type": "array",
          "items": { "type": "string" },
          "additionalItems": false
        }
      },
      "required": ["tag", "variants"],
      "additionalProperties": false
    },

    "_version": {
      "type": "object",
      "properties": {
        "tag": {
          "type": "string",
          "const": "_version"
        },
        "api": {
          "type": "string",
          "pattern": "^\\d\\.+\\d\\.+\\d+$"
        },
        "date": {
          "type": "string",
          "pattern": "^\\d+-\\d+-\\d+$"
        }
      },
      "required": ["tag", "api", "date"],
      "additionalProperties": false
    },

    "bcp47": {
      "type": "string",
      "pattern": "^(((en-GB-oed|i-ami|i-bnn|i-default|i-enochian|i-hak|i-klingon|i-lux|i-mingo|i-navajo|i-pwn|i-tao|i-tay|i-tsu|sgn-BE-FR|sgn-BE-NL|sgn-CH-DE)|(art-lojban|cel-gaulish|no-bok|no-nyn|zh-guoyu|zh-hakka|zh-min|zh-min-nan|zh-xiang)|(brv-(Thai|TH)-x-(dongluang|khongchiem|sakonnakon)|cek-(Latn-)?(MM-)?x-asangkhongso|cek-(Latn-)?(MM-)?x-khawngtuu|dao-(Latn-)?(MM-)?x-khengdaai|1901|1996|dgl-(Copt-)?(SD-)?x-oldnubian|ers-(Zzzz-)?(CN-)?x-ersushaba|fia-(Copt-)?(SD-)?x-oldnubian|mnc-(Mong-)?(CN-)?x-oldmanchu|nst-(Latn-)?(MM-)?x-moshanghawa|onw-(Copt-)?(SD-)?x-oldnubian|sgn-(Zxxx-)?MY-(Zxxx-)?MM|sgn-MY-Zxxx|sgn-Zxxx-MY-mm|tew-(Latn-)?(US-)?x-santaclara|tzo-(Latn-)?(MX-)?x-sanandres|tzo-(Latn-)?(MX-)?x-zinacantan|xnz-(Copt-)?(EG-)?x-oldnubian))|((([A-Za-z]{2,3}(-([A-Za-z]{3}(-[A-Za-z]{3}){0,2}))?)|[A-Za-z]{4}|[A-Za-z]{5,8})(-([A-Za-z]{4}))?(-([A-Za-z]{2}|[0-9]{3}))?(-([A-Za-z0-9]{5,8}|[0-9][A-Za-z0-9]{3}))*(-([0-9A-WY-Za-wy-z](-[A-Za-z0-9]{2,8})+))*(-(x(-[A-Za-z0-9]{1,8})+))?)|(x(-[A-Za-z0-9]{1,8})+))$"
    },

    "bcp47_variant": {
      "type": "string",
      "pattern": "^([0-9][a-zA-Z0-9]{3,8})|([a-zA-Z][a-zA-Z0-9]{4,8})$"
    },

    "iso639_3": {
      "type": "string",
      "pattern": "^[a-z]{3}$"
    },

    "iso3166_1": {
      "type": "string",
      "pattern": "^([A-Z]{2})|(\\d\\d\\d)$"
    },

    "iso15924": {
      "type": "string",
      "pattern": "^[A-Z]([a-z]{3})$"
    }
  }
}

Please note: the bcp47 pattern:

"pattern": "^(((en-GB-oed|i-ami|i-bnn|i-default|i-enochian|i-hak|i-klingon|i-lux|i-mingo|i-navajo|i-pwn|i-tao|i-tay|i-tsu|sgn-BE-FR|sgn-BE-NL|sgn-CH-DE)|(art-lojban|cel-gaulish|no-bok|no-nyn|zh-guoyu|zh-hakka|zh-min|zh-min-nan|zh-xiang))|((([A-Za-z]{2,3}(-([A-Za-z]{3}(-[A-Za-z]{3}){0,2}))?)|[A-Za-z]{4}|[A-Za-z]{5,8})(-([A-Za-z]{4}))?(-([A-Za-z]{2}|[0-9]{3}))?(-([A-Za-z0-9]{5,8}|[0-9][A-Za-z0-9]{3}))*(-([0-9A-WY-Za-wy-z](-[A-Za-z0-9]{2,8})+))*(-(x(-[A-Za-z0-9]{1,8})+))?)|(x(-[A-Za-z0-9]{1,8})+))$"

should not include the following:

|(brv-(Thai|TH)-x-(dongluang|khongchiem|sakonnakon)|cek-(Latn-)?(MM-)?x-asangkhongso|cek-(Latn-)?(MM-)?x-khawngtuu|dao-(Latn-)?(MM-)?x-khengdaai|1901|1996|dgl-(Copt-)?(SD-)?x-oldnubian|ers-(Zzzz-)?(CN-)?x-ersushaba|fia-(Copt-)?(SD-)?x-oldnubian|mnc-(Mong-)?(CN-)?x-oldmanchu|nst-(Latn-)?(MM-)?x-moshanghawa|onw-(Copt-)?(SD-)?x-oldnubian|sgn-(Zxxx-)?MY-(Zxxx-)?MM|sgn-MY-Zxxx|sgn-Zxxx-MY-mm|tew-(Latn-)?(US-)?x-santaclara|tzo-(Latn-)?(MX-)?x-sanandres|tzo-(Latn-)?(MX-)?x-zinacantan|xnz-(Copt-)?(EG-)?x-oldnubian)

which are the special cases to get the existing codes to pass. I felt it was important to validate the BCP-47 codes for structure as closely as possible given this is kinda a master list. The regex comes from: https://stackoverflow.com/a/7036171/1836776 and in the past I have compared it to and tested it fairly extensively against the standard.