As of February 1, 2017 passport holders of 40 countries, including the United States, are not required to arrange their tourist visas through a Vietnamese embassy or consulate, but can apply and pay for an electronic visa online.
The government website through which the e-visa application process are administered is http://www.immigration.gov.vn
According to the respective government decree, it will take three days to process the application, and the single entry e-visa validity will be limited to 30 days at a cost of $25. Since the e-visa issued is strictly a tourist visa, applicants do not require an invitation letter or a letter of guarantee.
Travelers holding a Vietnamese e-visa can enter the country through all international airports, most land borders, and seaports.