Hey Why vs Reactive Playground

Hey Why is a lightweight SQL EXPLAIN viewer for developers. Run EXPLAIN on your MySQL database or paste EXPLAIN JSON to see why your query behaves the way it does. • Explore execution plans by depth • Instantly see full scans, filesort, and temporary tables • Built for quick discussions without a laptop • Local-only. No cloud. No tracking.

Reactive Playground is a visual learning app for reactive programming. Instead of reading operator definitions only, you can play with marble timelines directly. Pick a category, open an operator, move events around, edit their values, clone items, remove them, or turn them into errors and completed events. The output updates live so you can understand what each operator really does. Explore operator categories such as: Transforming Filtering Combining Error Handling Utility Each playground shows a source timeline, an output timeline, a short explanation, and a code-style example. It is useful for learning ReactiveX concepts, reviewing operators, or quickly refreshing how a stream behaves before using it in code. Reactive Playground is made for developers, students, and anyone learning Rx-style reactive programming.