Open Source TypeScript Mechanical and Civil Engineering Software

OpenTakeoff is a free, Apache-2.0 quantity takeoff tool for construction estimating. Open a plan set (PDF, image or .zip), set the drawing scale, and measure - area, linear, count and deduct - with one-click room detection that traces a room when you click inside it. Apply waste percentages and supporting materials, then export quantities (SF, SY, LF, EA) as CSV or JSON. It runs entirely in your browser: no account, no upload, no server. Plans never leave your machine. What makes it different is who can run it. A person clicks the canvas; an AI agent calls the identical engine over the Model Context Protocol (npx opentakeoff-mcp, 35 tools) and gets the identical number, with the scale and origin of every measurement recorded. Built for Division 9 flooring by a working estimator, but the engine is general - drywall, paint, concrete, sitework. A free alternative to subscription takeoff tools such as STACK, PlanSwift, Bluebeam, Kreo and Togal.