Websites
I personally prefer Fandango. They're easy to use and have a very loose cancellation policy if you can't make the movie.
I use the AMC Stubs app I like it it's efficient and I get my tickets they send you an e-mail they scan it you're good to go
App or website
You can use their website or install their app. Or you can also buy it from Costco website which will actually be cheaper. Only catch is you need to buy in sets of 4 from Costco
Download the AMC app from the App Store or Google Play on your phone.
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