Do I Need an Appointment to Apply for an O Class Volunteer Visa at the Embassy in Hanoi?

Walk in walk out I did it 3 months ago 3 people in the q, easy, 10 minutes max the only advice I would say is what ever price your visa is, organize it in dollars first, that was a real pain in the bum not knowing that....if you need a great 5 star place to stay for 280bht a night 44 bo street, little Hanoi hostel boutique, I will stay there every time now, and every grab driver knows it. Enjoy.....I loved it"

You don’t need an appointment... just went last month.. need proof of 1,000 usd in bank, flight in and out of Thailand, two passport photos and US dollars to pay.

it is walk up service. They MIGHT ask for proof you're comin' back to thailand (but seeing as most people who get visas come right back that shouldn't be a problem ;) )