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const JSON Schema Keyword

Use const when a value must match exactly one JSON value, such as a discriminator, version marker, or fixed feature flag.

Validation

Schema template

Try in Validator

JSON Schema

{
  "const": "active"
}

Valid example JSON

"active"

Invalid example JSON

"inactive"

Fields

FieldTypeRequiredDescription
constany JSON valueYesDefines the single exact value that passes validation. Objects and arrays must match structurally.

How to use this schema

const is useful for discriminated unions, configuration versions, and fields that intentionally never vary within a schema branch.

Version support and combinations

This keyword or pattern is commonly supported across modern JSON Schema workflows. Check your validator for Draft-04, Draft-07, 2019-09, and 2020-12 behavior before relying on newer composition or conditional features.

Common combination: pair this reference with type, required, and properties so validation errors are specific enough for API clients and form users.

Batch validation seed

Want to validate JSON Schema in bulk? Toolumina Pro can grow into batch validation for 100+ files, saved schemas, and repeatable API contract checks.

Related reference pages

enum JSON Schema KeywordUse enum to allow only one value from a fixed set, such as a status, role, plan name, or integration mode.oneOf JSON Schema KeywordUse oneOf when exactly one schema in a list must match.if then else JSON Schema KeywordsUse if, then, and else to apply different validation rules based on a condition in the same JSON value.