JS1k
A yearly contest to write something impressive in no more than 1,024 bytes of JavaScript — the demoscene's size classes moved into the browser.
Peter van der Zee started JS1k in 2010 and kept it going for roughly a decade. The rules were simple: one file, at most 1,024 bytes, no external resources. The organiser supplied a ready-made page with a canvas element and short names such as a for the element and c for the drawing context, so no bytes had to be spent on setup.
Entries ranged from games and music to 3D scenes and fractals, and the contest grew its own toolchain. Packers like JSCrush and RegPack found repeated strings, replaced them with single characters and prepended an unpacker that ran the result through eval — the trick Crinkler played on Windows executables, done with regular expressions instead.