# Inserts or updates a foreign key

Inserts or updates the provided foreign key, if the supplied userId and key match.

Endpoint: PUT /v3/users/{userId}/foreign-key/update/{key}
Version: 2026-01-08
Security: ZephrHmacHttp

## Path parameters:

  - `userId` (string, required)
    Unique User identifier
    Example: "3f589a2d-86cd-4b70-a5df-68dca75a3a21"

  - `key` (string, required)
    Foreign system key
    Example: "foreign_system_key"


## Response 200 fields

## Response 404 fields