Opening PRJ files

Have a problem opening a .PRJ file? We collect information about file formats and can explain what PRJ files are. Additionally we recommend software suitable for opening or converting such files.

What is the .PRJ file type?

The primary association of the .prj filename extension goes together with the Projection Definition (PRJ) file type/format. A projection determines a reference coordinate system that will be used with a given geodetic dataset (an ESRI-compatible shapefile, GeoTIFF). Projection files follow the standard WKT (Well-Known Text) markup format developed by the Open Geospatial Consortium (OGC).

A .prj file is a plaintext ASCII definition of a projection in the WKT format. Projection files normally have numeric filenames (e.g., "27700.prj") based on EPSG (European Petroleum Survey Group) or other projection codes. PRJ projection files are auxiliary files that accompany shapefiles (.shp) which contain actual geodata. Although any .prj file can be opened and directly edited with a text editor, doing so requires knowledge of the base WKT format and its variants (OCG WKT, ESRI WKT).

PRJ projection files are widely used with a number of GIS applications, like ESRI ArcGIS/ArcView, ORBIT GIS, and many others. Open repositories of projection files (.prj) are available on the Internet.

As an abbreviation of 'Project,' the .prj extension serves to denote various project files created and used by numerous applications. A generic project file serves to save the current state of work in progress, with references to other files and resources involved in the project. PRJ files can be either text-based or binary, depending on the application. PRJ project files are commonly encountered in computer programming. IDE's (Integrated Development Environment) use compressed and/or encrypted binary .prj files for programming projects.

Project files (.prj) are intended to be opened and otherwise handled with the same application or program that was used to create them. Normally, .prj project files are not meant for direct distribution/publishing—instead, the project is rendered, compiled, or produced.

Besides, the .prj extension is also specifically associated with the AIMMS Project (PRJ) file type and format. Standing for "Advanced Interactive Multidimensional Modeling System," AIMMS is a highly advanced proprietary modeling, optimization, and problem-solving software system and IDE by AIMMS B.V. AIMMS uses .prj files to store project-specific GUI elements and settings. AIMMS project files (.prj) are always used together with model files (.amb).

Software to open or convert PRJ files

You can open PRJ files with the following programs:
UltraEdit by IDM Computer Solutions, Inc.
DesignSpark PCB
DesignSpark PCB by RS Components
Sybase PowerDesigner
Sybase PowerDesigner by Sybase Inc.

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