Great for visual use, solar imaging (inc. Approximate daytime / no polarscope polar alignment tool. Use device time/date/location, or enter your own, or pick from online & offline world databases via the Location Manager.
Most other apps do not perform precision calculations, so please only compare app readings to accurate sources (USNO, scientific software etc). Accurate calculation of Polaris or Sigma Oct for any date and location, including effect of atmospheric refraction (and annual aberration, nutation). If you have one not included, just ask the developer to add it! PoleMaster help view for South Hemisphere users. IOptron old & new, Astro-Physics RAPAS & PASILL, various versions of Takahashi EM-10/11/200/400/500, NJP, PM-1, P2-Z, the latest Orion / Skywatcher, the Classic Skywatcher / Orion / Celestron / Meade / EXOS2 / Bresser, the Telrad, Rigel QuikFinder, a couple for Astrotrac / Losmandy / Kenko / Avalon, the Vixen PF-L/Atlux/SX/SXD/SXP/AXD/GP/GP-DX/Polarie Polar Axis Scopes, a Konus and several Polar Finders: Tuthill, Explore Scientific 8x50, Meade 9圆0, Vixen Polaris, Celestron 7x50, Carton Optical. In the settings you can select the polar scope reticle that matches your own, from a vast collection: It is one of the few programs that are accurate in lower latitudes by correcting for atmospheric refraction (so expect results to agree only with precise software and not most simplistic "polar align" apps - see the "Accuracy" section in help for details). Polar Scope Align will calculate the position of Polaris or σ Octantis in your Polar Scope reticle for your location (using your phone's GPS or manually), allowing a quick and accurate polar alignment. Remember, all features & updates are free forever, the only in-app purchases are donations (tip jar).
Apart from the most reliable app for polar alignment (with or without a polar scope), PS Align pro has become the astronomer's swiss-army knife with all the tools added over the years.