- it's apparently written in "FASM" assembler, which is BSD-licensed (according to Wikipedia), cross-platform, self-hosting (?), Intel-syntax (my preferred camp), and also has an experimental "g" version supporting output targetting JVM, AVR & other fancy stuff (customizable via "macroinstructions"): http://www.flatassembler.net/download.php
- IIUC, this "hnwatch" page is at the same time kinda delicate & non-pushy advertisement for the author's (authors'?) multipurpose ASM library named "HeavyThing" (i.e. kinda custom "stdlib"): https://2ton.com.au/HeavyThing/ (which seems to be required to build "hnwatch"? It wasn't clear to me initially) - worth some more highlight, I believe.
As a sideways wishful-thinking comment regarding the highlighter used for showcasing the hnwatch sources: I'd much prefer if syntax was not highlighted (i.e. the eye-piercing blue '[' & ']'), but instead the "call" instructions would, as well as "jmp" and variants (with a different colour), user symbols (different colour again) including especially labels (another colour please). Also, if there were somewhat more comments in the sources. Also, in https://2ton.com.au/library_as_html/hnwatch/textify.inc.html, the highlighter seems to have gone awry.
update: edited heavily to hopefully better express my positive attitude; in the Interwebs, no one can see you smile