Turn one JSON config into a converting, self-contained Gumroad landing page. No API keys, no build server, no internet at build time. The output is a single HTML file you can host anywhere or paste into Gumroad. What you get One JSON in, one HTML out. Fill in a title, price, and a few feature cards. Run one command. Get a single self-contained landing.html you can host anywhere or paste into Gumroad. Sanitizer-safe by design. The page renders even if Gumroad strips the styles or scripts. Base state is visible, not hidden, so a stripped page still looks right instead of blank. Gumroad overlay wired in. Buy buttons ship with the data-gumroad-action and data-gumroad-field attributes. Point them at your product URL and the in-page checkout overlay just works. Accessible and mobile-first. Skip-to-checkout link, visible focus outlines, reduced-motion support, and a responsive dark or light layout that reads cleanly on a phone. No cloud, no keys. Pure Python plus Pillow. Runs offline, prints nothing to a server, sends your copy nowhere. Your product, your machine. Want the PDF too? This builds the page. The paid Gumroad Product + Landing Generator also turns your Markdown into the PDF you sell, bundles the zip and ships the fonts. Code LAUNCH takes €7 off for the first 20 buyers. Ships with an AGENTS.md so Claude Code or Cursor can drive it directly: the config keys, the two buy-button hrefs no config file can set, and the sanitizer-safe rule not to break.