UserId Mapping allows you to map existing userIds (from your old auth provider) to the SuperTokens userIds. This prevents you from having to updat the existing userIDs in your application's table.
As an example, if after creating the user in SuperTokens, their userId is
fa7a0841-b533-4478-95533-0fde890c3483 and the existing userId for that user is
customUserId, then you can map these user IDs by calling the following API:
curl --location --request POST '/recipe/userid/map' \
--header 'api-key: ' \
--header 'Content-Type: application/json' \
Now whenever this user signs in, or if you fetch information about this user from SuperTokens, their userID will be
The maximum allowed size of the
externalUserId is 128 characters.