Typst is a typesetting system, so an alternative to TeX, LaTeX, &c. It's free and open source software (FOSS), but if you visit typst.app it looks like you're meant to sign up for something then use it on the web. But you can download and install it locally, just like any good FOSS product. If you're fortunate enough to click on the github link, you'll find instructions for installing it locally…