There used to be multiple tools like this from different websites, but they were all bought by Calligraphr to redirect to them instead, giving them an effective monopoly and letting them charge subscription fees for generating fonts over the limits of the free version. I used to create two fonts and merge them with FontForge to get a complete usable font.

Great to see some competition on the market. Completely in the browser would mean it does not depend on a server and continues working as an archived version, so that's certainly great.