I use Trello to manage all my projects and todos.
I'm not a fan of code formatter, but I often need to read and debug the JSON data responded from the server.
https://www.freeformatter.com/css-beautifier.html#ad-output
https://www.epochconverter.com/
http://tomeko.net/online_tools/file_to_hex.php?lang=en
Convert a binary file to C style hex array. Useful to embed binary stuff in code.
https://mbebenita.github.io/WasmExplorer/
Useful to test small code piece.
[https://www.musictheory.net/tools]
Tools to help learning music theory
Reduce png/jpg file size dramatically.
http://www.wbwip.com/wbw/emailencoder.html
Hemingway App makes your writing bold and clear
Improve your grammar