To maintain your digital continuity you may need to convert file formats, as file formats naturally age and can become more risky, but also because your business may change how it needs to use its information, or because your technology environment changes. A number of tools are available to convert document files to suit your preference.
Document conversion tools
IlovePDF
Ilovepdf interface document conversion
Tutorial on how use Ilovepdf to convert files
Convertio
Convertio document converter
Tutorial on how use convertio to convert document files
Zamzar
Zamzar document conversion
Tutorial on how use Zamzar to convert document files
FreePDFconvert
freepdf document conversion tool
SmallPdf
Small pdf document converter
Are these entirely free, they are not paid for, or you can upgrade on some features, Thank you for the effort.
Most are free but I would recommend I love pdf to use. It does most functionality free