I do quite like convert.io for quick online image conversions.
Very good extension library
I think you get 5 for free.Every day.
But if you need more, just go incognito or VPN.
One very minor thing I don’t like about it, Is it will save it to your downloads. You can’t direct it to save it to a specific folder.
Like I say very nitpicky/ first world problem; otherwise, it’s a really good tool.