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The enum keyword restricts an instance to a fixed set of allowed values.

​
Syntax

The value of enum must be an array. This array should have at least one element, and elements should be unique. 
{
  "enum": [value1, value2, value3, ...]
}

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Validation Rules

An instance validates successfully if its value is equal to one of the elements in the enum array. Equality is determined using the rules defined in the JSON Schema Core specification.

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Examples

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String Values

{
  "enum": ["red", "green", "blue"]
}
Valid instances: 
"red"
"green"
"blue"
Invalid instances: 
"yellow"
"Red"
"RED"

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Numeric Values

{
  "enum": [1, 2, 3, 5, 8, 13]
}
Valid instances: 
1
5
13
Invalid instances: 
4
6
"5"

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Mixed Types

{
  "enum": ["active", "inactive", null, 0, false]
}
Valid instances: 
"active"
null
0
false
Invalid instances: 
"unknown"
true
1

​
Status Codes

{
  "type": "object",
  "properties": {
    "status": {
      "enum": ["pending", "approved", "rejected"]
    },
    "priority": {
      "enum": [1, 2, 3, 4, 5]
    }
  }
}
Valid instance: 
{
  "status": "approved",
  "priority": 3
}

​
Complex Values

{
  "enum": [
    {"type": "success", "code": 200},
    {"type": "error", "code": 400},
    {"type": "error", "code": 500}
  ]
}
Valid instances: 
{"type": "success", "code": 200}
{"type": "error", "code": 400}

​
Notes

  • Elements in the array can be of any type, including null
  • String matching is case-sensitive
  • While elements should be unique, duplicate values will be treated as the same constraint
  • The enum keyword is useful for defining finite sets of valid values like status codes, categories, or configuration options

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