OTF is a font file. Contents of OTF files Files with OTF contain OpenType font definitions. OpenType standard was jointly developed by Adobe and Microsoft. OTF font standard aims to be the universal font standard supported by all software and hardware platforms.
After converting the file to the new format, you will be able to use other programs to support it. Keep in mind, however, that the FFIL file after converting to OTF may differ slightly from the original. The most important information should be kept, but if you want the file after conversion from FFIL to OTF to be the same, you have to do this carefully and choose the proper application from the list below.
There is no guarantee, of course, that the conversion will come up to all your expectations, but it will certainly help you. If, after all, the effect of converting FFIL to OTF does not meet your expectations, you can simply try to find on the Internet a different version of your file in FFIL format, properly converted to a OTF file by someone else. If this fails, use the information provided in the further part of the website.
Unfortunately, if after performing the two previously described steps (trying to find your FFIL file converted by someone else, and the attempt to convert it to OTF on your own) you still have a problem with your file, then there are only a few solutions left. You can once again try to find and install an application that can open the FFIL file in its original format (without conversion to OTF file). Such a solution will be difficult to implement, but it certainly will give the best result.