Most of the hiking and biking apps on the market today share inaccurate GPS tracks and illegal routes, oftentimes over environmentally sensitive areas and across private property. The routes are shown on inadequate terrain maps without any field-checking.
During the past 17 years, I've been surveying thousands of trails across the United States and writing software that makes sense of the data. This website is like an encyclopedia of trails that provides free access to more than 350,000 Adobe PDF topo maps. I built software to convert the most current full-sheet topo maps into the compact JPEG file format with my surveyed trails overlaid on the maps. These are JPEG topo maps designed for the outdoors. Each map includes embedded data holding boundary information for applications to show your location. Load the maps into any image editing software, even Microsoft Paint, and draw your own tracks and notes on the maps. I want these maps to be free for everyone, because researching how to safely and responsibly explore the outdoors shouldn't require an app that charges an annual fee.