Birdfont is a font editor which lets you create vector graphics and export TTF, OTF, and SVG fonts. The editor has good support for both monochrome and color font formats.
Calligraphr transforms your handwriting or calligraphy into a real vector font. You can specify different variants for each character, and they will be used randomly during writing to give your font a more natural look.
Glyphr Studio is a web-based font designer focusing on font design for hobbyists. It has vector editing tools, full Unicode (BMP) support, import and export capabilities, and more.
FontForge is a FOSS font editor that allows you to create and modify postscript, truetype, and opentype fonts. You can save fonts in many different outline formats and generate bitmaps.