Graphic converter

For a long time, I was looking for a software to convert various image formats like BMP, GIF, JPG, PNG and many others. So I was searching online and then I found this software graphics-converter-pro.com. But I have to pay 49$ to use all the functions of this software.Now I am looking for similar softwares.So if anyone knows other alternatives, please reply here and message me.
Thank you!!

You can use Imagemagick it is free and it can be installed on Windows, Linux and Mac.

It does not have a GUI and I use a batch file on windows.

There’s no need to pay for this kind of utility - there are plenty free alternatives like irfanview or faststone that will perform any image conversion task you are likely to need