# Check if user exists

Check if a user already exists by email. Wise uses email address as unique identifier for users. If email has already been used by a user, it cannot be reused to create a new user.
Note that this uses a `client-credentials-token` and not a `user access_token` for authentication.

Endpoint: POST /v1/users/exists
Security: ClientCredentialsToken

## Security:

  - `ClientCredentialsToken` (unknown)
    http bearer JWT

## Header parameters:

  - `X-External-Correlation-Id` (string)
    Optional UUID for correlating requests across systems. If provided, Wise echoes it back in the response. Maximum 36 characters. [Learn more](/guides/developer/headers/correlation-id).

## Request fields (application/json):

  - `email` (string, required)
    User's email address.
    Example: test@wise.com

## Response 200:

  - `200` (unknown)
    OK - Successfully checked user existence.

## Response 200 fields (application/json):

  - `exists` (boolean)
    Whether a user with this email already exists.

## Response 200 headers (application/json):

  - `X-External-Correlation-Id` (string)
    Echoed back when `X-External-Correlation-Id` was included in the request. [Learn more](/guides/developer/headers/correlation-id).
    Example: f47ac10b-58cc-4372-a567-0e02b2c3d479

  - `x-trace-id` (string)
    Unique trace identifier assigned by Wise. Useful when contacting support about a specific request.
    Example: fba501b6d453b96789f52338f019341f

## Response 429:

  - `429` (unknown)
    Rate limit exceeded. Retry after the number of seconds specified in the `Retry-After` header.

## Response 429 headers (application/json):

  - `Retry-After` (integer)
    Number of seconds to wait before retrying the request.
    Example: 5

  - `X-Rate-Limited-By` (string)
    Identifies the rate limiter that triggered the 429 response.
    Example: wise-public-api

  - `X-External-Correlation-Id` (string)
    Echoed back when `X-External-Correlation-Id` was included in the request. [Learn more](/guides/developer/headers/correlation-id).
    Example: f47ac10b-58cc-4372-a567-0e02b2c3d479

  - `x-trace-id` (string)
    Unique trace identifier assigned by Wise. Useful when contacting support about a specific request.
    Example: fba501b6d453b96789f52338f019341f