What Free Online Tool Do You Wish Existed?

Hi everyone,

I'm building a free online tools website and would love to hear what tools people actually need.

Many websites are overloaded with ads and unnecessary features, so I'm trying to create lightweight tools that solve real problems quickly.

Current project:
https://free-tools-hub200.blogspot.com/

What tool would make your daily work easier? Any suggestions are welcome and may be added to the site.

Thanks!