I have a detailed specification (shared as a .docx file) for a small desktop tool that will read order-export files from three marketplace platforms and turn them into a two Slovak Post XML file ready for upload. • Input formats – Amazon: tab-delimited .txt – Etsy: .csv – eBay: .csv The GUI must run smoothly on Windows and macOS. I would like it written in Python so the final build can be packaged with PyInstaller or a similar solution into double-clickable apps for both systems. All field mappings, constants, and any “fixed” values need to sit outside the codebase in a human-readable configuration file (JSON, TXT, or whatever you find most convenient). Changing a parameter, column mapping should never require touching the source; simply editing the config must be enough. Key acceptance criteria • Correctly parses each marketplace’s native export without manual pre-processing • Generates XML that validates against the Slovak Post schema supplied in the docx • Configuration file(s) let me change column names, fixed strings, and default values • Simple, clear GUI: choose input files, pick output folder, press “Generate” • Packaged executables for Windows and macOS plus full, well-commented source I’m not in a rush, so we can agree milestones that make sense for both of us. I am looking for a reasonable price, a working but simple application.