JSON & Schema

JSON Schema Arrays

An array schema describes both the collection and its members. Use items for a repeated item schema and collection keywords for length or uniqueness rules.

Published Aug 11, 2026

Smallest useful schema

Describe the collection, then its items

Array only

{ "type": "array" }

String items

{
  "type": "array",
  "items": { "type": "string" }
}

Live validation task

Diagnose one invalid array item

The third item violates the repeated string item schema.

Schema: { "type": "array", "items": { "type": "string" } }
Data: ["red", "blue", 42]

Expected result: The real validator reports the numeric item at index 2; changing 42 to "42" makes the data valid.

After the failing item is fixed

Add only the constraints the data needs

Arrays of objects

Put object properties under the item schema, not directly on the array.

Collection limits

Use minItems, maxItems and uniqueItems for list-level rules.

Tuple-style data

In draft 2020-12, prefixItems describes fixed leading positions.

Practice with the full tool

Validate your array schema

Use your own schema and JSON data to inspect item-level validation errors and paths.

Continue in JSON Schema Validator →