CADbox marker is a free software available for download from the Apple Store. It can be used by Builders, Contractors, Architects and others who have an account on CADbox (www.cadboxplus.com) to view construction drawings, punch up lists and other documents. Drawings can be marked up with annotations of various shapes, texts and color, and shared instantly with other users of CADbox sharing the folders and files. CADbox is a cloud enabled file sharing and collaboration software from CoralTree, Inc., San Jose, CA. It is used for sharing Construction drawings, Markups, Autodesk Revit and AutoCAD project files, with builders, architects and contractors. CADbox has enhancements for active collaboration - files are locked before a user can make changes. After the user closes the file, CADbox will sync the changes to the other users and release the lock automatically. This simple to use locking and syncing technology patented by CoralTree, Inc. avoids conflicted copies and errors, allowing users to collaborate and work on project files hassle free. Architects can print and save construction drawings in PDF format so builders and contractors can view the drawings on their iPad. They can markup or annotate drawings using the markup tools provided and share with the architects so they can edit the project files and regenerate the drawings for quick turn around. There is no need to carry bulky print outs to job sites or making handwritten markups which improves the overall efficiency and experience of all the users.