Eta

Eta is a lightweight, embedded, pluggable, and super-fast JS template engine. Developed as an alternative to EJS, Eta is more lightweight, faster, and solves several parsing problems (like closing delimiters inside strings, multi-line comments, and left whitespace trimming) with other template engines like doT and EJS.

Eta weighs only around 2.2 KB gzipped. It works both online and on Node.js, and (since it's built in TypeScript) exports TypeScript types.