Ryanair

CAUTION!!! Absolutely the worst app I have ever used! Ryanair tells you you have to download the app to check in. Then you must choose a luggage option. If you have already paid for a luggage option in advance, they charge you a second time because you cannot go to the check-in page without choosing an option - ONCE AGAIN, even if it was the option you already paid for!! I was charged both directions and ended up paying an additional $184 for a flight that originally cost $293!!!

Cheap flights, but you get what you pay for. Check in through the app has to be done 24hrs in advance (the app frequently crashes when trying to do this), or they ask you to pay to check in when you get there. I also purchased parking through the app, but it does not provide a location for the service. The temperature in flight was very hot and uncomfortable even with the vents open...during the winter. Good enough for a short flight, but I wouldn't travel too far with Ryanair.

Used a 3rd party app to pay for my flight. Turns out this app is too stupid to understand how to work around 3rd party apps when every other app can. I've used multiple apps that can accomodate to my legitimate purchase while this is the only one that can't. My guess is they do this on purpose to make money off of people. I was charged 55 euros because I couldn't check in (had the correct reference number wrong email APPARENTLY). I tried their "contact us" option and I couldn't even access it.