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Data Mapper Preview

Visualize and test JSON data mapping transformations with live preview

Mapping Rules

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n8n Expression Code

// n8n Set node expression for data mapping
// Paste this in a Code node or use Set node fields

// first: {{ $json.user.firstName }}
// last: {{ $json.user.lastName.toUpperCase() }}
// email: {{ $json.user.email.toLowerCase() }}
// city: {{ $json.user.address.city }}
// skills: {{ $json.user.tags.join(', ') }}

JSON Path Syntax

Path Examples

$.user.name - Nested property

$.items[0] - Array index

$.data.tags[2] - Nested array

$ - Root object

Transformations

uppercase/lowercase - Change case

trim - Remove whitespace

split(delimiter) - String to array

join(delimiter) - Array to string

default(value) - Fallback value

JSON Data Mapper & Transformation Preview Tool

When building n8n workflows, you often need to transform data between different formats. API responses rarely match the structure your next node expects. This data mapper tool helps you visualize and test JSON transformations before implementing them in your workflows.

Common Data Mapping Challenges

  • API returns nested data but you need flat structure
  • Field names don't match between source and destination
  • Need to combine or split values
  • Data types need conversion (string to number, etc.)
  • Missing fields need default values

How to Use This Tool

  1. Paste your source JSON - The data you're receiving
  2. Define mapping rules - Source path → Target path
  3. Add transformations - Modify values as needed
  4. Preview output - See the result in real-time
  5. Copy n8n expressions - Use in your workflows

Use Cases for n8n Workflows

API Integration

Map external API responses to your database schema or CRM fields.

Data Migration

Transform data structure when moving between systems.

Webhook Processing

Normalize incoming webhook payloads from different sources.

Report Generation

Reshape data for email reports or dashboard displays.

Why Use a Data Mapper Preview?

  • Faster debugging - See results instantly without running workflows
  • Visual feedback - Understand complex transformations
  • Error prevention - Catch path errors before deployment
  • Expression generation - Get ready-to-use n8n code

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