OpenType with CFF outlines is what type foundries ship: cubic Bezier curves inherited from PostScript, plus the advanced typography tables that make ligatures and alternates work. Structurally it is a TrueType file with a different flavour tag and different outline data.
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 an OTF file above and choose afterwards.