Preventing duplicate Items

Identify duplicate Items during Link using the onSuccess callback

Prefer to learn by watching? A video guide is available for this topic.

Duplicate Item adds

When a user links their financial institution account through Plaid, a new Item is created. Two Items created for the same set of credentials at the same institution will be considered different and not share the same item_id. Preventing a user from accidentally linking an Item they have already linked can help avoid confusing behavior in your application and will also prevent you from potentially being billed for both Items.

Preventing duplicate Item adds with onSuccess

First, make sure you have placed the Plaid Link drop-in behind a user login, so that you can have access to any Items already associated with the same user. Then, before requesting an access_token, first examine the onSuccess callback metadata and compare it to the user's existing Items. You can compare a combination of the accounts’ institution_id, account name, and account mask to determine whether your user has previously linked their account to your application.

Example implementation

For an example implementation, see Plaid Pattern, a sample app that has implemented simple server-side logic that checks whether the user ID and institution ID pair already exist in the application database. The relevant code can be found in items.js.