Faviconer - Faviconer.com, or favicon generator, is online tool for creating favicon.
Icon Converter by RedKetchup - Convert a PNG, JPEG, WEBP, HEIC, GIF, TIFF, BMP, or SVG image to the ICO format. Customize the icon background and rounded corners. Create a compatible Windows ICO file from an image.
ConvertIcon! - Converticon is a simple icon utility.
IcoFX - IcoFX is an all-in-one solution for icon creation, extraction and editing.
Ordinatore - Those who want to tidy up their Macs will surely love this application.
png2ico - Program to convert .PNG files to a Windows icon resource, such as used for website/bookmark icon favicon.ico. Available for different platforms.