curl --request POST \
  --url https://api-{dc}.moengage.com/v1.0/custom-templates/osm/search \
  --header 'Authorization: Basic <encoded-value>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "page": 1,
  "entries": 10,
  "template_source": [
    "API"
  ],
  "sort_params": [
    {
      "last_modified_date": "DESCENDING"
    }
  ]
}
'

{
  "data": [
    {
      "meta_info": {
        "template_id": "1234567890123",
        "template_name": "NAME_OF_THE_TEMPLATE",
        "template_version": "1",
        "created_by": "[email protected]",
        "channel": "ON-SITE",
        "template_source": "API",
        "template_type": "CUSTOM"
      },
      "external_template_id": "4a1afbc5-4c31-4f19-8c23-793e27af01aa",
      "version": 1,
      "basic_details": {
        "payload": "<html>...</html>",
        "preview_image": "https://pbs.twimg.com/profile_images/10ydbKG1.jpg"
      },
      "created_by": "[email protected]",
      "created_at": "2023-08-01T07:58:53.880000",
      "updated_by": "[email protected]",
      "updated_at": "2023-08-01T07:58:53.880000"
    }
  ]
}

{
  "error": {
    "code": "400 Bad Request",
    "message": "Validation failed because of invalid request data",
    "details": [
      {
        "code": "MissingValue",
        "target": "external_template_ids",
        "message": "external_template_id or version is missing in external_template_ids."
      }
    ],
    "request_id": "npmQrbNE"
  }
}

{
  "response_id": "OUUkHvcn",
  "type": "custom_template",
  "error": {
    "code": "Too Many Requests",
    "message": "API rate limit breached. Current limit: n/m mins"
  }
}

{
  "title": "Internal Server Error",
  "message": "An unexpected error was encountered while processing this request. Please contact MoEngage Team"
}