Lua

Lua is the surprise pick and the most argued-about ranking on the testing panel. Lua is embedded in NGINX via OpenResty, Redis scripting, Roblox with 70 million daily users, and increasingly in AI inference engines as a configuration language. It is tiny at around 280KB, blazingly fast for a scripting language, and trivial to embed in C applications. The niche is real: if you work in game development, NGINX performance engineering, Redis scripting, or IoT firmware, Lua knowledge pays dividends no other scripting language can. It is the most targeted language on the list — useless outside its niches, transformative inside them.