TrueType is the font format Apple designed and Microsoft adopted, and it is still what most desktop fonts are. Its outlines are quadratic curves, and its tables - glyphs, metrics, character maps - sit in a directory the file checksums against itself.
Every conversion below runs in this page, on your own machine. Nothing is uploaded, there is no queue, and there is no account to make. Pick a target format, or just drop a TTF file above and choose afterwards.