12-30-2013 8:16 AM
Thanks for posting. It appears that the HTC One does not have a built-in flashlight app, but you can download one from the Google Play Store.
To do so, simply click on the Google Play icon and search for "flashlight." You'll see quite a few results, but you should be able to sort by reviews.
Let me know if you have any questions or concerns!
12-30-2013 9:15 AM
Personally I use the Swiss Army Knife app. It has a few other goodies besides the flashlight. I've just checked to see if the flashlight works on the AT&T HTC One and it does.