How to convert RGB to CMYK?

„Your print provider does not accept RGB images? You have to deliver images in the CMYK colorspace but you don’t have access to a professional tool to convert an image from RGB to CMYK?With this free online tool you can convert your images from RGB to CMYK color space using a professional ICC profile.“ (Source https://www.rgb2cmyk.org/, 11.11.24)

Rgb2cmyk.org is a free online tool that allows you to upload an RGB document and generate it with a CMYK color profile in either JPG or TIF format. (Source https://logosbynick.com/export-cmyk-with-inkscape/, 11.1.24)