stewdio/q.js

q.js is a legacy educational project (over 7 years old) that implements basic quantum gate simulations in JavaScript. While it achieved a respectable 362 stars, its development has completely stalled (0.0 velocity), and it lacks the features required for modern quantum research, such as noise modeling, transpilation, or hardware integration. It is fundamentally a 'visualizer' rather than a 'platform.' It has been superseded by much more powerful tools like IBM's Quantum Composer, which provides a professional-grade drag-and-drop interface, and Quirk, which is the gold standard for browser-based interactive quantum toy models. From a competitive standpoint, there is no moat; the math behind simulating a few qubits is standard linear algebra, and the UI patterns have been refined significantly by frontier labs and dedicated quantum software startups. Platform domination risk is high because cloud providers (AWS, Azure, IBM) provide these tools for free to lock users into their hardware ecosystems.