Online Tourist visa to Vietnam

Well the truth is people are getting their "letters of approval" from those  online visa agencies. There are quite a few of them and their charges are more or less the same.
Since they are all private agencies, most VN embassies advise travelers not to go through them.

The process is:
- You apply online and pay their service fee.
- After 3 days they will email you your "letter of approval"
- you take a print  of that letter and on arrival, submit it at the airport VoA counter along with your PP, 2 copies of a recent photo and the Visa Application Form.
- You pay the stamping fee   ($25 for single entry, 1 month)
That's it. Your visa will be pasted on your PP.

These days, it doesn't take much time to get a VoA.
Pay the stamping fee in USD cash (fresh currency bills preferred).
Be careful about the date-of-arrival you mention when you apply for your "letter of approval".
Your approval letter may/may not contain multiple travelers' names. No worries as long as the date-of-arrival, your name and your PP no. are correct.
- a sample letter

Here's a recent thread on VoA.
- https://www.expat.com/forum/viewtopic.php?id=686057

Hi Libhero,

visafoto.com/en/vietnam_visa_photo_online

I will update this thread with my experiences from the processes of applying for Vietnam visa on arrival. I will be objective as possible to help other people too.

Timeline

--21 Nov 2017. I posted here and asked members to respond. Two persons did and I read all I could.
--3 Jan 2018. I applied for Vietnam VOA with www.vietnamvisa.govt.vn and got an email receipt ($17 fee) and a promise to get visa approval letter in 2 days via email. I am waiting.

--4 Jan 2018. I received official letter of approval for visa on arrival in my email. They took 13 hours to process my application. They accurately wrote all my information on the letter. No problem. Now I wait to see how this letter plays out at the airport in Ho Chi Minh City. Please visit again  to read my final updates Thank you. JGL.

--17 Jan 2018. Final update. I arrived to Ho Chi Minh City Airport Jan 16, went to the landing visa office. I presented approval letter, 2 passport photos, and in 15 minutes I was called back and paid $25 for single entry.

Caution#1. You cannot get multiple entries at immigration if you applied for single entry. The officer said it is impossible. I thought I could get a multiple entries at immigration to exit,  visit Thailand, and return before flying back to US. But no, no way. My approval letter said single entry only.

Caution#2. It is easy to join the all passport line if you don't know that you first must head to landing visa office that is straight ahead of you. After you get the visa then you come to join the all passport line to exit.

Thanks to all of you who followed this thread. I hope it gave you confidence to use the visa on arrival. It is faster, hassle free, and cheaper.

Caution #3. Immigration officer took only one passport photo and returned one to me. I did not see why they requested 2 anyways. They require a 4 x 6cm size. Most photographers in US set cameras at 2x2 inches. Use the 2x2 and it works well. Don't be confused by the 4x6 cm requirements, which you probably will not find in USA.