SunCalc v2 – a tiny JavaScript library for sun and moon calculations
15-year-old library revived with 20x moon accuracy verified against US Naval Observatory.

Zero-dependency HTTP client with caching, but native fetch covers most needs.
Frontend developers
Axios · Ky · Got
15-year-old library revived with 20x moon accuracy verified against US Naval Observatory.
2x faster than Bun on warm installs, but only Linux/macOS and monorepo support missing.
Combines singleflight with a context-scoped per-request cache so concurrent and subsequent callers share one in-flight call and instant cached results, respectively. Typed Key[T] generics and a tiny API (WithCache/Get) make it trivial to add to middleware, and the zero-allocation claim targets the micro-optimizations Go teams care about.
Syncpack is a pragmatic, focused tool: it finds/fixes version mismatches, enforces version policies, can ban packages, and even source truth from specific packages — all from the CLI. The v14 Rust rewrite is a meaningful engineering move (likely faster and more robust) rather than a vanity bump, and the docs show sensible commands like npx syncpack list/update and workspace-aware discovery. Not revolutionary — this space has other solutions — but if you run a large monorepo and care about semver hygiene, it’s the kind of low-friction tool you’ll actually keep in devDependencies.
Live chaos testing for HTTP clients when you need to pick between axios and fetch.
Semantic caching with dependency invalidation beats standard Redis wrappers for agent costs.