Hugo:
https://gohugo.io/

PaperMod:
https://github.com/adityatelange/hugo-PaperMod/

GitHub Pages:
https://pages.github.com/

GoatCounter:
https://www.goatcounter.com/

instant.page:
https://instant.page/

KaTeX:
https://katex.org/

Mermaid:
https://mermaid.js.org/

Tabler Icons:
https://tabler-icons.io/

Google Forms:
https://www.google.com/intl/ja_jp/forms/about/

Maybe inspired:

Show related posts:
https://github.com/adityatelange/hugo-PaperMod/pull/1049

Adding a render-link hook:
https://github.com/adityatelange/hugo-PaperMod/discussions/542

Add margin top to certain single elements surrounded by code blocks for consistency:
https://github.com/adityatelange/hugo-PaperMod/pull/1128/

fix: Adjust margin-bottom in nested lists:
https://github.com/adityatelange/hugo-PaperMod/pull/1284

Magnific Image Pop-Up Modal for Hugo:
https://gist.github.com/zjeaton/0cdd7e4bed9d292ab6f3d76b0369f16d

Modal Image Pop-up:
https://compassionate-feynman-1e69e9.netlify.app/modal/

Hugoの画像を自動で圧縮する方法:
https://kakudo.org/blog/auto-image-compression-in-hugo/

Hugo でエスケープの問題を回避しつつ KaTeX を使う:
https://www.oshikiri.org/posts/use-katex-in-hugo/

Overview of Hugo/PaperMod, modifying PaperMod, and comparison to al-folio:
https://jessewei.dev/blog/2023/papermod/

makeの第二引数をMakefileで扱う:
http://puni56.net/posts/makefile-arg/

オッズに合う - Hugo:
https://joni.jp/categories/hugo/

アロハル - Hugo:
https://aloha-ru.com/hugo/

k-kaz が Hugo で遊ぶサイト:
https://k-kaz-git.github.io/

mokuzine.net - hugo:
https://mokuzine.net/tags/hugo/

まくまく Hugo ノート:
https://maku77.github.io/hugo/

ひよこまめ Hugo:
https://blog.chick-p.work/tags/hugo

Nelis Oostens - Hugo:
https://oostens.me/posts/hugo/

hugo-PaperModX:
https://github.com/reorx/hugo-PaperModX

hugo-WonderMod:
https://github.com/Wonderfall/hugo-WonderMod

hugo-BurgerMod:
https://github.com/mylesagray/hugo-BurgerMod

hugo-shortcode-roneo-collection:
https://github.com/RoneoOrg/hugo-shortcode-roneo-collection

hugo-plus:
https://github.com/H4tch/hugo-plus

hugo-modules:
https://github.com/gethugothemes/hugo-modules

hugo-leaflet:
https://github.com/altrdev/hugo-leaflet

hugo-video:
https://github.com/martignoni/hugo-video

hugo-cloak-email:
https://github.com/martignoni/hugo-cloak-email

In addition, many others, all dependency, thanks!