curl --request POST \
  --url https://api.notifly.tech/set-user-properties \
  --header 'Authorization: <api-key>' \
  --header 'Content-Type: application/json' \
  --data '{
  "projectId": "example_project_1234567890abcdef",
  "userId": "user_abc123"
}'

{
  "data": 3
}