Your handwriting, as a realttf. Write four lines in a notebook you already own, photograph the page, type in your own hand. The browser fits the notebook rules, dewarps the page, removes the ruling, and segments all 81 glyphs. Only 1-bit bitmaps cross the wire, about 100KB. The server traces them and assembles the font.
Every tool in this space makes you print a template sheet first. Calligraphr has existed for years and still needs a printer. This one reads ordinary ruled notebook paper, so the step that loses most people never happens.
It's for every people who want to type in their own handwriting. The reason I built this is that the output is identity rather than utility, so people post it without being asked.