Compare Lists and Identify Common Items & Differences Using Custom Keys

Description

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:
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
Performs a field-based comparison using the specified key
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": "[email protected]", "name": "Alice" },
{ "email": "[email protected]", "name": "Bob" }
],
"listB": [
{ "email": "[email protected]", "name": "Bobby" },
{ "email": "[email protected]", "name": "Carol" }
]
}

Output:
common: [ { "email": "[email protected]", "name": "Bob" } ]
onlyInA: [ { "email": "[email protected]", "name": "Alice" } ]
onlyInB: [ { "email": "[email protected]", "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.