platoseedRunKit is the best tool for prototyping server-side JavaScript. RunKit notebooks remove the friction of trying new ideas. With one click, you'll have a sandboxed JavaScript environment where you can instantly switch node versions, use every npm module without having to wait to install it, and even visualize your results.
Formerly βTonicβ Β· why startups rename β

Bun is an incredibly fast all-in-one JavaScript toolkit

Collaborative in-browser IDE