Do airlines employ dynamic pricing to increase prices to some users but not others, for example when someone is searching a fare repeatedly might the airline charge them more?

This wouldn't be very practical given that you can search for that same airfare on an OTA and get the cheaper price. Airlines price tickets into fare buckets, so there's not some algorithm that says "charge this person $20 more if they search 10 times" - airline pricing just doesn't work that way.

The suspicion is not unwarranted. Sometimes I have the same feeling. It can not be excluded that certain IT functionalities/algoritme lead to increase of the fare tied to repeated fare searches for the same city pairs. Admittedly, I have absolutely no scientific grounds for my suspicion...

I don't think it's possible to target a specific person with an algorithm alone, especially across TAs, interline and codeshare tickets, and other sales channels. If there's a global increase in searches for specific tickets, dates, or airports, they could use that data to change prices for everyone, but one person alone shouldn't make a difference.

But it's probably possible for airlines to do it locally on your browser, using cookies or based on your account or frequent flyer number. I don't how that would work on the back end though, whether it's changing fare bucket availability, adding surcharges, or something else. And of course it wouldn't work if you just didn't log into any accounts, switched computers or browsers, and/or used private browsing mode. So do any of those things if you're worried about it.

I've heard anecdotes from people that it's happening to them, but I'm skeptical that it's widespread, especially when so many other factors affect ticket pricing and availability in real time.

This is what I meant/was referring to.

I was convinced Delta did this in the 2000s. Seemed every time I redid a previous search, the fare increased. And then, when I cleared my cookies, the price declined. The experts on the Delta forum told me I was nuts, but I was convinced. At some point, though, that pattern stopped.

It seems far more likely that this is a trick of memory (or fare caching) as opposed to targeted re-pricing. But of course, the only way to test it is to actually write down what you were charged on a search and then compare to a fresh browser/incognito mode.

It is becoming more possible (in principle) with dynamic pricing pilots like @ UA. It is definitely not happening today though and I am pretty sure it would be met with 'regulations' to prohibit it, if that became a thing.