tl;dr: Bastardica is a browser-based tool for creating "bastard" fonts by mixing two OpenType fonts, with options to stretch, squish, and apply effects to the mix-in glyphs at configurable strides (prime numbers recommended to avoid collisions). Everything runs locally via Pyodide and fontTools, outputting standard OpenType files that work anywhere ligatures are supported. Note that mixed fonts are derivative works, so licensing of both source fonts applies for commercial use.