wtf is imposium?

Imposium is a small desktop application that helps you prepare a PDF for printing using a technique called imposition, which means arranging pages so that when a stack of paper is printed on both sides and folded, the pages end up in the correct reading order. You choose a PDF, and the app shows you exactly how the pages will be arranged onto A3 sheets, front and back, in the order they will print. Once you are happy with the layout, you download the finished, imposed file. If the PDF you upload has a number of pages that is not a multiple of four, Imposium automatically adds blank pages at the end so the layout still works out evenly. This saves you from adding filler pages yourself before printing. The easiest way to use Imposium is to download a ready made release for your operating system rather than building it from source. On a Mac, the app is not signed with an Apple developer certificate, so macOS will initially block it from opening. The README explains how to allow it through System Settings, or by running a single command in the terminal, and this should only need to be done once. Windows and Linux releases exist too, though the developer notes they are untested on those platforms and asks for feedback on whether they work. If you would rather run the project from its source code instead of a packaged release, you install a Python tool called uv, clone the repository, and run one command to start the app. The project is built in Python and uses a framework called flet for its interface. The README notes that Claude, an AI assistant, was used to help get the project to a working state and to write and debug its build script. No license information is given in the README.