This conversion seems to represent transformation of FontoForge Spline font databases (.sfd) to an OpenType font file (.otf). It appears that you can perform this sfd to otf conversion with several dedicated font converters, including FreeFont Converter or the Online Font Converter.
Convert Fontforge Spline Font database file format to OpenType font file format.
We have found 2 software records in our database eligible for .sfd to .otf file format conversion.
On-line services software - convert sfd to otf on web
FreeFontConverter is an on-line tool used for free font conversion.
Convert from sfd file
to otf file
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned sfd to otf. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
Online font converter is a web tool that offers conversions of various font formats, including many exotic formats. It should support most of the common formats for Mac and PC.