epoberezkin/ajv

{
  "$schema": "https://json-schema.org/draft/2019-09/schema",
  "$id": "https://json-schema.org/draft/2019-09/meta/core",
  "$vocabulary": {
    "https://json-schema.org/draft/2019-09/vocab/core": true
  },
  "$recursiveAnchor": true,

  "title": "Core vocabulary meta-schema",
  "type": ["object", "boolean"],
  "properties": {
    "$id": {
      "type": "string",
      "format": "uri-reference",
      "$comment": "Non-empty fragments not allowed.",
      "pattern": "^[^#]*#?$"
    },
    "$schema": {
      "type": "string",
      "format": "uri"
    },
    "$anchor": {
      "type": "string",
      "pattern": "^[A-Za-z][-A-Za-z0-9.:_]*$"
    },
    "$ref": {
      "type": "string",
      "format": "uri-reference"
    },
    "$recursiveRef": {
      "type": "string",
      "format": "uri-reference"
    },
    "$recursiveAnchor": {
      "type": "boolean",
      "default": false
    },
    "$vocabulary": {
      "type": "object",
      "propertyNames": {
        "type": "string",
        "format": "uri"
      },
      "additionalProperties": {
        "type": "boolean"
      }
    },
    "$comment": {
      "type": "string"
    },
    "$defs": {
      "type": "object",
      "additionalProperties": {"$recursiveRef": "#"},
      "default": {}
    }
  }
}