A project is a folder: a form, a layout, a script that builds the pages, and assets such as images and fonts. Save it as a single .yatate file to move or share it.

my-project/
  project.ypf           <- name, description, default page size
  form.json             <- the form
  process.js            <- builds the pages (required for any output)
  overlay.canvas        <- a layout, placed by process.js
  validate.js           <- (optional) cross-field validation
  autocomplete.json     <- (optional) suggestion lists
  presets.json          <- (optional) saved form values
  preview.png           <- (optional) a preview image for the library
  logo.png, Custom.ttf  <- images, fonts and PDFs, flat in the folder

The files are JSON (.ypf, form.json, .canvas, .grid, ...) or JavaScript. Edit them in the app, in any text editor, or both. Generated PDFs are not stored in the folder; see the generation pipeline.