Modest JavaScript framework from Basecamp/DHH that augments server-rendered HTML with controllers attached via data attributes. Part of the Hotwire stack. In Yaroslav Shmarov's wroclove.rb 2022 talk used for dropdowns, tabs, checkboxes, debounced submit, copy-paste, hotkey shortcuts, auto-clicking hidden links to open modals on page load, and re-submitting hidden buttons to trigger dynamic form re-renders (country→state→city). Emphasis: a few lines of Stimulus massively extend what Turbo Frames and Streams can do, and all three can be used independently. DHH has promoted it for about three years per a wroclove.rb 2018 panel.