Overwrite users in a list

API at a glance

Description: This API overwrites all users in a custom user list with users from an S3 file. All existing users in the list will be replaced.

Authentication & testing

Testing the API on this page

How to try it here

Use your User API Key as the Username (leave Password blank).

Select the appropriate API endpoint based on your Blueshift region.

Enter the necessary parameters and click Try It to run the request.

Authentication using Base64 encoding

Note for developers

API requests require authentication using HTTP Basic Authentication with an API key. The API key serves as the username, while the password field should be left empty. The format to encode is: your_api_key: (note the trailing colon).

This string must be Base64-encoded and included in the request's Authorization header as follows:

Authorization: Basic encoded_value

You can generate the encoded value using a trusted Base64 encoder.

Postman collection

Try it with Postman: Explore the API using Blueshift's Postman collection.

Things to know before you start

List ID required: Obtain the list ID from the Create empty list response or from the Blueshift dashboard.

You can find the list ID in the URL when viewing a custom user list in the Blueshift app. For example, if you open a custom user list in the Blueshift app, its URL looks like https://app.getblueshift.com/dashboard#/app/custom_list/<LIST_ID>/edit.

Destructive operation: This completely replaces all existing users in the list. Existing users will be removed.
S3 file required: Upload your file to the Blueshift S3 bucket, recommended location: import/custom_lists/.
File format: File must contain user identifiers (email addresses or customer IDs) matching the list's source type.
Use case: Best for bulk list updates, replacing entire audience segments, and syncing lists from external sources.

Request parameters

Check out the request parameters

Path parameters

Parameter	Type	Required	Description
`list_id`	`integer`	✅ Yes	ID of the list to overwrite.

Body parameters

Parameter	Type	Required	Description
`s3_file_path`	`string`	✅ Yes	S3 path of the file containing user identifiers. Recommended location: `import/custom_lists/` in Blueshift S3 bucket.

Example requests & responses

Overwrite users in list

{
  "s3_file_path": "import/custom_lists/users_list.csv"
}

{
  "status": "ok"
}