Good question—this kind of tool is actually a great example of where frontend-first makes more sense.
For a Morse code translator, the core logic (encode/decode, audio playback, UI interaction) can be handled entirely on the client side using JavaScript. That keeps it fast, offline-friendly, and easier to maintain. Full-stack only becomes necessary if you want things like user accounts, history saving, or analytics per user.
i found this js tool most likely gret looking and simple https://morsecodetranslatr.com/
If the goal is just translation + practice, frontend is usually the most efficient and scalable starting point.