You can get Vietnam Visa on arrival by following these simple steps:

• All you need to do is, Fill a application form online.
• Pay the Visa Servicing Fees.
• Within 2 working days, you can get an email with official “Vietnam Visa Approval Letter” issued by the Vietnam Immigration Department.
• Print the “Visa Approval Letter” and have 2 passport size photographs.
• Along with your passport, When you arrived the Destination Airport, show your Visa Approval letter with Photographs and stamping fee with entry-exit form at immigration office.

For more info :- https://www.vietnammyvisa.org/apply-online/