Techniques are described for facilitating and/or optimizing a transaction, such as a purchase transaction, through the use of scanned data. In some implementations, a user may use a portable computing device to scan a vehicle tag (e.g., vehicle identification number) that is affixed to a vehicle and determine vehicle information. The user may also scan a user tag such as a driver's license to determine user data that identifies the user. The vehicle data and/or user data may be communicated to transaction service(s), which generate transaction data that may be specific to the particular user that provided the vehicle data and/or user data. The transaction data may include information regarding a price of the vehicle, terms of a loan that the user may take out to finance the purchase of the vehicle, information regarding an insurance policy for insuring the vehicle, and so forth.