Compare Lists and Identify Common Items & Differences Using Custom Keys

This workflow compares two lists of objects (List A and List B) using a user-specified key (e.g. email, id, domain) and returns:

• Items common to both lists (based on the key)
• Items only in List A
• Items only in List B

How it works:

1. Accepts a JSON input containing:
   • listA: the first list of items
   • listB: the second list of items
   • key: the field name to use for comparison
2. Performs a field-based comparison using the specified key
3. Returns a structured output:
   • common: items with matching keys (only one version retained)
   • onlyInA: items found only in List A
   • onlyInB: items found only in List B

Example Input:

{
  "key": "email",
  "listA": [
    { "email": "alice@example.com", "name": "Alice" },
    { "email": "bob@example.com", "name": "Bob" }
  ],
  "listB": [
    { "email": "bob@example.com", "name": "Bobby" },
    { "email": "carol@example.com", "name": "Carol" }
  ]
}

Output:

• common: [ { "email": "bob@example.com", "name": "Bob" } ]
• onlyInA: [ { "email": "alice@example.com", "name": "Alice" } ]
• onlyInB: [ { "email": "carol@example.com", "name": "Carol" } ]

Use Cases:

• Deduplicate data between two sources
• Find overlapping records
• Identify new or missing entries across systems

This workflow is useful for internal data auditing, list reconciliation, transaction reconciliation, or pre-processing sync jobs.