I was unable to find a thread on this topic that interest me a lot.

The following airlines are reported have "Bid for Upgrade" programs.

If you know of others, please post them. If you believe an airline posted does not have such a program, please post it.

Admins: if there is a thread somewhere, please move this, or delete and provide a link.

Thank you!

Aer Lingus
Airberlin
Air Astana
Air Canada
Air China
Air France
Air Mauritius
Air New Zealand
American Airlines
Avianca
Austrian Airlines
Brussels Airlines
Cathay Pacific
Copa Airlines
Czech Airlines
Austrian
El Al
Estonian Air
Ethiopian Airlines
Etihad
Garuda
Hawaiian Airlines
Icelandair
KLM
LOT
Lufthansa
Malaysian Airlines
Philippine Airlines
Qantas
Royal Brunei Airlines
SAS
Singapore Airlines
Sri Lankan Airlines
TAP Portugal
Virgin Atlantic
Virgin Australia

Common platforms for this are
http://www.plusgrade.com/
https://www.optiontown.com/

SAS (SK) is another one

I believe SQ does as well.
​​​

Ethiopian Airlines does too.

I was given the opportunity on an Air France flight a couple of years ago.

Thank you for the additions. I have updated the original post.

The thing is that across different airlines policies are vastly different. SQ, AFAIK, allows upgrades only from fully flexible Economy Y fare class and only to their PE class, while LH allows from cheap economy to Business. Probably it worth to mention such policy differences.

Air Canada has one.

Royal Brunei has a bid for upgrade program

Air Astana (KC) has one as well.

The Lufthansa one seems a bit like a scam to me. On my last LH booking, LH offered me fixed price upgrades and "bid for upgrade". The minimum you could select in "Bid for upgrade" was only marginal smaller than just paying for the upgrade straightaway.

The prices for both upgrade possibilities were more expensive than buying straightaway the higher class. No doubt that it will be interesting to those suffer under the Y only travel policies and are willing to pay out of their own pocket for a little more comfort, but traveling privately it doesn't necessarily make sense.

Probably depends on a route. I've upgraded from economy to Premium Economy on KUL-FRA route for 900RM which was less than $200.

Philippines Airlines.

List in original post updated.

I plan to look for good "bid to upgrade" flights on future international travel....probably premium economy to business. All my travel is personal and at 6'5" and 71 years of age, I want adequate legroom. Premium economy is OK but business is much better if the price is right.

CX does not have this. They trialed it a while back but dropped it.