Answers.Body: <p>The "external identifier" field on contact records is available so you don't need a custom field. It won't allow duplicates.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2019-07-31T17:26:18.273Z
Answers.LastActivityDate: 2019-07-31T17:26:18.273Z
Answers.UserDisplayName: Demerit
Body: <p>I want to add a custom field that we use as an ID from a 3rd party. I need to ensure this value is unique as a way to prevent duplicates. What is the best way to do this?</p>
  
Tags: <civimember><contacts><custom-fields><duplicate-contacts>
Title: Unique custom field - contact creation
ThreadText: # Unique custom field - contact creation
  
  (Asked by: username_0 on 2019-07-31)
  
  I want to add a custom field that we use as an ID from a 3rd party. I need to ensure this value is unique as a way to prevent duplicates. What is the best way to do this?
  
  **Tags:** civimember, contacts, custom-fields, duplicate-contacts
  
  
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  ## 1 answers
  
  ### Answer by username_1 on 2019-07-31. Score: 7
  
  The "external identifier" field on contact records is available so you don't need a custom field. It won't allow duplicates.
  
  
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