PeakIdentify benefited from the Open Source app Show Me Hills by Nik Cain (www.showmehills.com).
The data include the original Show Me Hills database plus additional peaks that were not included in the original. In particular, the original database was missing some of the most prominent peaks in the US State of Washington, since those were categorized as "volcanoes" by www.openstreetmap.org and not as "peaks".
Unfortunately, many (~ thousands) of the peaks in the www.openstreetmap.org database have their heights entered in feet by their submitters, instead of in meters, as it should have been. I have corrected the heights of those based on the height given by the Digital Elevation Map (DEM) files. However, there could still possibly be some mistakes left over from the original www.openstreetmap.org database.
For the USA, additional peaks were obtained from The United States Board on Geographic Names (USBGN). Where there was a difference between the Openstreetmap and USBGN databases the height and/or name from the USBGN was adopted.
The DEM files were downloaded from www.viewfinderpanoramas.org/dem3.html. Those in turn are largely based on the 2000 Shuttle Radar Tomography Mission (SRTM). Although most of the voids in the original SRTM files have been filled by Jonathan de Ferranti, there were still some voids left, which I filled based on a simple bilinear interpolation. PeakIdentify makes use of 1 arcsecond DEM files (where available), 3 arcsecond DEM files, as well as 9 arcsecond DEMs generated by averaging the 3 arcsecond data. For the closest peaks the 1 arcseconds DEMs are used (if available for the current location), while for the farthest peaks the 9 arcsecond data are used.