FileProInfo.com is the file information database of over 15,000+ file types, software, free online apps/tools, so tools, guest blogs, videos, and images.
I must say I have found https://fileproinfo.com the best online and free file converter ever.
Everything about files, software and free online tools.
Found great information about file extensions, software and also found the relative free online tools.
Convertio - File Conversion in the Cloud
Ui Thumbnail Generator - A simple way to generate thumbnail. For docs and demos.
File-Extensions.org - Large computer file extension library with detailed explanation of each file type with links to download free or associated software programs.
FilePreviews - Thumbnails and metadata for almost any kind of file
FileInfo.com - FileInfo is the central file extensions registry and contains a database of over 10,000 file types.
Blog Cover - Cover image generator for your blog post