Does incognito make flights cheaper? No. Opening a private window, clearing your cookies, or switching browsers before you search does not lower the price an airline shows you. The trick has been passed around for years, usually as "they track your searches and jack up the price when you come back," and it refuses to die because the story is satisfying and the price does sometimes change. Those two facts feel connected. They aren't.
What actually sets the fare
Airline pricing runs on the seat, not on you. A fare is tied to the route, the date, how many seats in each price bucket are still open, and how demand is tracking against the airline's forecast for that flight. When a cheap bucket sells out, the next search returns the next bucket up, and it does that for everyone looking at once, incognito or not. The person searching from a different city on a different device sees the same jump at the same moment.
There's no cookie in your browser that tells the airline "this one really wants Rome, charge more." The systems doing the pricing don't work at the level of your individual browsing history, and building a per-shopper surcharge into a public fare would be a mess to run and easy to catch. What people read as personalized gouging is almost always the inventory moving under them.
Why so many people swear by it
Because the price really did drop sometimes right after they cleared cookies, and the brain files that as cause and effect. What actually happened is that fares move on their own, constantly, and if you look twice with an hour or a day between, you'll often catch a different number. Clear your cookies or don't, the fare was going to be different anyway. It's the same reason there's no magic day or hour to book: the thing you did right before the price changed rarely caused the change.
The real lever isn't a browser trick, it's timing and flexibility. A single fare swings more inside one week than any private-window ritual could ever save you, so the win comes from looking often enough to catch the dip when it lands. That's the boring, honest version of the advice, and it's the one that works.
So we don't sell you a trick. We check your saved routes every morning and send the three best fares we found that day, no cookie-clearing required. If a price drops, you hear about it because we looked, not because you opened the right kind of window.