Android barcode app in Flutter — a local, offline library of the short strings you have to show someone: carrier codes, Wi-Fi, addresses, record numbers. Home-screen widget, Quick Settings tile, 25 symbologies, URL-safety heuristics, no ads and no network code. Closed source.
Configuration service in Go — JSON key-path read/write over HTTP or a raw TCP protocol, append-only persistence, optional Raft cluster mode. One binary, no database server; benchmarked against etcd and Consul.
Alpine.js router — declarative routes, dynamic params, external templates, hash or HTML5 history modes, zero runtime dependencies.
Svelte router without SvelteKit (Svelte 3/4/5) — dynamic params, custom regex constraints, wildcard routes, hash or HTML5 history modes.
Node.js template engine (npm, 2011) — Shaun's first npm package, published in the Node v0.4 era. A piece of open-source history.