ream.js
A comprehensive, functional datetime library for JavaScript/TypeScript with immutable data structures, real IANA timezone database support, DST handling, and a plugin system
a0-tzmigration-js
A NPM package that helps migration between timezone changes when they happen in the tzdata/zoneinfo/Olson database
iana-db-timezones
Auto-generated IANA timezone data with rich metadata, no dependencies, full TypeScript support, and Node/browser compatibility.