I just need to validate my JSON:

• https://jsonformatter.org/

I need to test my Javascript in a node environment:

• http://repl.it/

I need to test basic html/css/js:

• https://codepen.io/

I want to install NPM packages/major frameworks too:

• http://codesandbox.io/
• https://stackblitz.com/

Via https://scotch.io/tutorials/7-javascript-playgrounds-to-use-in-2019