JBM Ballistics has to be one of the best if not the best. http://www.jbmballistics.com/ballistics/calculators/calculators.shtml It has a huge library of bullets or you can enter your own info if not in the library. I have found it to be extremely accurate and reliable. It does take a little bit of learning to understand all the inputs. The good news is that all those things light sight height are remembered so you dont have to input them again even months years later. Unless you are using a very different gun setup.
I’ve used an android app called applied ballistics. I’ve hung around with @sungazer abit and compared it with jbm, and it was always spot on providing the info was good, used it in friendly comps and worked really well
My personal preference is Strelok Pro. Gets me within a couple clicks @1000yds with the 6.5CM. I’ve got all the rest and always come back to Strelok for its ease of use and world class support. Igor is very responsive to emails and his FB Support page. I’m not a fan of Applied Ballistics as the dope can vary from version to version which is a concern, also I’ve met Bryan Litz and he’s a dick.