Markdown by DaringFireball - Text-to-HTML conversion tool/syntax for web writers, by John Gruber
IDA - The best-of-breed binary code analysis tool, an indispensable item in the toolbox of world-class software analysts, reverse engineers, malware analyst and cybersecurity professionals.
Typora - A minimal Markdown reading & writing app.
HxD - HxD is a carefully designed and fast hex editor which, additionally to raw disk editing and...
StackEdit - Full-featured, open-source Markdown editor based on PageDown, the Markdown library used by Stack Overflow and the other Stack Exchange sites.
WinHex - WinHex hex editor, disk editor, RAM editor. Binary editor for files, disks, and RAM. Download HEX EDITOR. Sector editor. Drive editor.