Good Neighbor Gun Dealer Act This bill directs the Department of Justice (DOJ) to create and publish a voluntary code of conduct (i.e., Good Neighbor Code of Conduct) that urges licensed gun dealers to take steps to prevent the sale of firearms to individuals prohibited from purchasing firearms, implement a safety plan to detect and deter firearm theft, cooperate with law enforcement investigations, and ensure that a completed background check precedes a firearm sale. DOJ must certify and publish a list of Good Neighbor gun dealers who comply with the code of conduct. The bill permits DOJ to publicly disclose firearms trace data unless such disclosure undermines an investigation or compromises law enforcement efforts or public safety. DOJ must submit to Congress a strategic plan to improve firearms trace data, identify licensed dealers who transfer firearms used in crimes, and increase enforcement efforts against licensed gun dealers who violate firearm laws.