This is a free service. It comes with ABSOLUTELY NO WARRANTY.
You retain the full ownership of the material you submit to RealFaviconGenerator.net (in particular, the pictures). You also have the full ownership of the generated material (pictures, other files, HTML code...). In other words:
You are responsible of the usage you make of RealFaviconGenerator.net. In particular, by using RealFaviconGenerator.net, you declare that you have the right to use the submitted and generated pictures, the way you use them. For example, if you use some copyrighted material to build your next web site's favicon, you are responsible of this copyright infrigement, not RealFaviconGenerator.net.
You are not allowed to use the non-interactive API to build your own favicon generator web site. In other words, you cannot build a web site similar to RealFaviconGenerator.net and delegate the actual generation to RealFaviconGenerator.net. However, you can build clients similar to clients offered by RealFaviconGenerator.net. For example, you can build your own Gulp plugin that uses the non-interactive API, even if RealFaviconGenerator.net comes with its own Gulp plugin.