House Planner holds the design of your house in one browser workspace, from true-scale floor plans drawn over a satellite photo of your plot to costed wiring, plumbing, sewer, and heating layouts. Draw walls at true scale in millimetres with thickness and materials, add doors, windows, garage gates, and furniture with true dimensions, and watch room areas and plot coverage total as you work. Flip into 3D for a massing model or the house finished with material textures and facade colours, with cut-down walls for reading the layout from above. Every utility network gets an engineering layer: route sewer lines to a septic tank with slopes and cleanouts, auto-route electrical circuits with breaker and voltage-drop checks, and run water piping from well and boiler to each fixture. Underfloor heating loops lay out room by room, split before 80 metres, and balance flow against heat loss. The bill of materials computes quantities from the plan and networks, producing a priced estimate you can print, tick off as you buy, or export to CSV. Every save is a numbered version with restorable snapshots, tabs cannot overwrite each other, and the JSON plan can be edited by an AI assistant through the same API. One password guards the project, phones get a read-only view for on-site checks, and the whole thing runs in one Docker container with no database. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.