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JSON Schema is used in Workflow Builder to define the expected structure of step outputs and validate data throughout workflow execution.

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What is JSON?

JSON (JavaScript Object Notation) is a structured way to represent information that computers can easily understand. Human language: “A person has a name Ravi and age 26.” JSON version: 
{
  "name": "Ravi",
  "age": 26
}

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Data types

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Objects

Containers for multiple fields using { } with key-value pairs: 
{
  "name": "Ravi",
  "age": 26
}
Keys must be wrapped in double quotes. This is invalid:
{ name: "Ravi" }

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Numbers

Numeric values without quotes: 
{
  "age": 26,
  "price": 99.99
}

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Strings

Text values wrapped in double quotes: 
{
  "name": "Ravi",
  "city": "Mumbai"
}

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Booleans

Simple true/false values: 
{
  "isActive": true,
  "isVerified": false
}

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Arrays

Lists of values using [ ]: 
{
  "fruits": ["apple", "banana", "orange"],
  "numbers": [1, 2, 3]
}

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Null

Empty or undefined values: 
{
  "middleName": null
}

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What is JSON Schema?

A JSON Schema defines the rules and structure that data must follow. Think of it as a blueprint that tells the system:
  • What fields are expected
  • What type each field should be
  • Which fields are required

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Example schema

{
  "type": "object",
  "properties": {
    "name": { "type": "string" },
    "age": { "type": "number" },
    "gender": { 
      "type": "string", 
      "enum": ["male", "female", "other"] 
    }
  },
  "required": ["name"]
}
This schema says:
  • Expect an object with name, age, and gender fields
  • name must be a string and is required
  • age must be a number
  • gender must be one of the allowed values

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Key schema properties

PropertyDescription
typeThe data type (object, array, string, number, boolean)
propertiesField definitions for objects
requiredArray of required field names
enumAllowed values for a field
itemsSchema for array elements

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Using schemas in workflows

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Output schemas

Define the expected output structure for steps: 
{
  "type": "SYS_SUB_WORKFLOW",
  "name": "Verify Customer",
  "outputSchema": {
    "type": "object",
    "properties": {
      "verified": { "type": "boolean" },
      "verificationId": { "type": "string" }
    },
    "required": ["verified"]
  }
}

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Validation

Output schemas are used for:
  • Validation - Ensure step outputs match expected structure
  • Tooling - Help the editor infer available data fields
  • Documentation - Self-documenting workflow definitions

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JSON Schema builder

For non-developers, Workflow Builder includes a visual JSON Schema Builder that lets you create schemas without writing code:
  1. Add a field
  2. Choose its type (text, number, boolean, date)
  3. Mark if it’s required
  4. Set allowed values (for enums)
The builder converts your choices into proper JSON Schema automatically.

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Common patterns

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Nested objects

{
  "type": "object",
  "properties": {
    "customer": {
      "type": "object",
      "properties": {
        "name": { "type": "string" },
        "email": { "type": "string" }
      }
    }
  }
}

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Arrays of objects

{
  "type": "object",
  "properties": {
    "items": {
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "id": { "type": "string" },
          "quantity": { "type": "number" }
        }
      }
    }
  }
}

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Optional fields with defaults

{
  "type": "object",
  "properties": {
    "status": { 
      "type": "string",
      "default": "pending"
    }
  }
}

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Next steps

DSL types

Learn about the workflow DSL type system

Validation rules

Understand workflow validation