The following is a message from HFPilot:
HFPilot is your go to app for estimating HF propagation – navigate the HF skies with confidence with an app that works offline, giving estimated frequencies and times for points around the world!
The goal of HF Pilot is to do for shortwave/HF radio what RepeaterSTART revolutionized for repeaters: Get propagation data, EVEN OFFLINE, install on your computer and know what hour to tune your radio, and connect with operators around the world.
The program is available from https://hearham.com/HFPilot. It is completely free and open source for Linux and Windows desktop, and there is also an minimal iOS and Android version available for $1.99.
Source: HFPilot