[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"extension:v3:en:prj":3},{"resolvedFromAlias":4,"canonicalExt":5,"ext":5,"name":6,"category":7,"categoryName":8,"updatedAt":9,"popularity":10,"summary":11,"howToOs":12,"quickAnswer":18,"answerIntro":19,"whatIs":20,"description":21,"furtherReading":22,"openInstructions":38,"commonIssues":52,"securityNotes":71,"faq":74,"aliases":84,"mimeTypes":85,"relatedExtensions":86,"breadcrumbs":131,"categoryAnchor":141,"categoryFuturePath":142,"metaDescription":143,"availableHowToOs":144,"openOnDeviceLinks":145,"cannotOpenReasons":161,"cannotOpenFixes":162,"convertOptions":163,"securityAffiliateMessaging":164,"securityAffiliates":165},false,"prj","ESRI/Shapefile Projection (WKT CRS) File","gis","GIS","2026-06-12T08:57:24.251Z",55,".prj is a plain-text “projection” sidecar file most commonly used with ESRI Shapefiles to store the dataset’s coordinate reference system in Well-Known Text (WKT). You typically open it in GIS software (as part of the shapefile) or a text editor to inspect the CRS definition.",[13,14,15,16,17],"windows","mac","linux","ios","android","To open .PRJ files on Windows, if you have the full dataset, open the shapefile (.shp) in your GIS application; it will load the coordinate system from the same-name .prj automatically.","To open a .prj file, the most common approach is to open the associated shapefile (.shp) in a GIS program; the software will read the matching .prj automatically. If you only need to view what it contains, open the .prj in any text editor because it is plain text WKT describing a coordinate system/projection.","A .prj file is a companion projection file that defines a coordinate system and map projection as text. In the shapefile workflow, it is stored with the same base name as the .shp (for example, wells.shp uses wells.prj) and typically contains a WKT description of the CRS (often in an ESRI-flavored WKT).","In everyday GIS use, “.prj” most often refers to the shapefile projection file: a small, human-readable text file that stores the coordinate reference system definition in Well-Known Text (WKT). When a shapefile is moved between computers or shared, the .prj is how GIS software knows what the coordinates in the .shp mean.",[23,26,29,32,35],{"title":24,"url":25},"Fundamentals of a shapefile's coordinate system—ArcGIS for Desktop Help","https://desktop.arcgis.com/en/arcmap/10.3/manage-data/shapefiles/fundamentals-of-a-shapefiles-coordinate-system.htm",{"title":27,"url":28},"Well-known text representation of coordinate reference systems (WKT-CRS)","https://en.wikipedia.org/wiki/Well-known_text_representation_of_coordinate_reference_systems",{"title":30,"url":31},"Geospatial position of CAD and BIM data—ArcGIS Pro Documentation (Esri PRJ file)","https://pro.arcgis.com/en/pro-app/latest/help/data/revit/geospatial-position-of-cad-and-bim-data.htm",{"title":33,"url":34},"Shapefile (Wikidata item)","https://www.wikidata.org/wiki/Q278934",{"title":36,"url":37},"GDAL documentation downloads (includes ESRI WKT / wkt_esri references)","https://gdal.org/_/downloads/en/release-3.10/pdf/",{"windows":39,"macos":42,"linux":45,"ios":48,"android":50},[40,41],"If you have the full dataset, open the shapefile (.shp) in your GIS application; it will load the coordinate system from the same-name .prj automatically.","To inspect the CRS text, right-click the .prj and open it with a text editor (it should look like WKT).",[43,44],"Open the associated shapefile (.shp) in a GIS application; the matching .prj is read automatically if it has the same base name.","To view the contents, open the .prj in a plain-text editor to see the WKT coordinate system definition.",[46,47],"Open the shapefile (.shp) in a GIS application; it will use the same-name .prj file when present.","To view or copy the CRS definition, open the .prj in any text editor (it is plain text WKT).",[49],"If you need to read the CRS, open the .prj in a text viewer/editor app; for full GIS use, transfer the shapefile set to a desktop GIS program that reads the .prj automatically.",[51],"Open the .prj in a text viewer/editor app to inspect the WKT; for reliable GIS import, use a desktop GIS program that reads the shapefile + .prj together.",[53,59,65],{"title":54,"description":55,"steps":56},"The shapefile loads in the wrong place or with “unknown CRS”","This often happens when the .prj is missing, renamed, or does not match the shapefile base name, so the GIS software cannot determine the coordinate system parameters.",[57,58],"Verify the .prj exists in the same folder as the .shp and shares the exact same base name (for example, wells.shp and wells.prj).","If you received only a .prj file, obtain the full shapefile component set and keep the filenames consistent.",{"title":60,"description":61,"steps":62},"The .prj opens but looks like confusing text","A .prj is expected to contain WKT (Well-Known Text) describing a coordinate reference system. This is normal and is meant for software to parse rather than for manual reading.",[63,64],"Look for WKT elements such as a PROJCS/GEOGCS-style structure; this indicates it is a projection definition.","Use GIS software to interpret it by opening the associated shapefile so the CRS is applied automatically.",{"title":66,"description":67,"steps":68},"CRS definition seems incompatible between programs","Different software may expect slightly different WKT “flavors”; shapefile .prj files commonly use an ESRI WKT variant, which can lead to differences when importing or translating CRS definitions.",[69,70],"If a program reports WKT parsing issues, check whether it expects ESRI WKT vs another WKT form and re-export or convert the CRS definition in the target tool.","When using geospatial conversion tools, choose an input option that supports ESRI WKT if available.",[72,73],".prj files are plain text and typically do not contain executable code, but they are still untrusted input: malformed WKT can trigger bugs in GIS parsers.","Treat a lone .prj as incomplete context: it is usually meaningful only alongside its dataset (for example, a shapefile). Apply it only to data you trust to avoid misinterpreting coordinates and producing incorrect analyses or maps.",[75,78,81],{"question":76,"answer":77},"Is a .prj file required for a shapefile?","A shapefile can exist without a .prj, but then the coordinate system may be unknown to software. When present, the .prj stores the coordinate system parameters for the shapefile using the same base name.",{"question":79,"answer":80},"What is inside a .prj file?","It contains a coordinate reference system definition written in Well-Known Text (WKT). In many GIS workflows it is ESRI-style WKT that defines the projection and coordinate system.",{"question":82,"answer":83},"Why does my GIS software ignore my .prj?","The most common reason is filename mismatch: the .prj must share the same base name as the .shp (and be in the same folder) so the software can find it automatically.",[],[],[87,93,98,104,109,114,119,125],{"ext":88,"name":89,"category":7,"categoryName":8,"popularity":90,"summary":91,"howToOs":92},"geojson","GeoJSON (RFC 7946) geospatial data",72,".geojson is a JSON-based format for exchanging geographic features (points, lines, polygons) and their properties. It is widely used in GIS and web mapping tools and follows the GeoJSON standard (RFC 7946).",[13,14,15,16,17],{"ext":94,"name":95,"category":7,"categoryName":8,"popularity":90,"summary":96,"howToOs":97},"shp","Esri Shapefile (geometry file)",".shp is the main geometry file in an Esri Shapefile dataset used to store vector GIS features. You typically open it in GIS software (for example ArcGIS Pro) together with its companion files such as .dbf and .shx.",[13,14,15,16,17],{"ext":99,"name":100,"category":7,"categoryName":8,"popularity":101,"summary":102,"howToOs":103},"kml","Keyhole Markup Language (KML)",70,"KML is an XML-based GIS format for showing geographic features (placemarks, paths, polygons, overlays) on maps and virtual globes. It’s commonly opened in Google Earth and is also supported by GIS tools such as ArcGIS.",[13,14,15,16,17],{"ext":105,"name":106,"category":7,"categoryName":8,"popularity":10,"summary":107,"howToOs":108},"gpkg","OGC GeoPackage (SQLite) geospatial database",".gpkg is an OGC GeoPackage: a SQLite 3 database file with a standardized schema for geospatial data. It commonly stores vector layers and can also store raster/tiles in the same single file.",[13,14,15,16,17],{"ext":110,"name":111,"category":7,"categoryName":8,"popularity":10,"summary":112,"howToOs":113},"osm","OpenStreetMap OSM XML (map data)",".osm is an OpenStreetMap dataset stored as OSM XML, containing map features like nodes, ways, and relations. It’s commonly opened or imported into GIS tools such as QGIS, GDAL-based software, or data-integration tools like FME.",[13,14,15,16,17],{"ext":115,"name":116,"category":7,"categoryName":8,"popularity":10,"summary":117,"howToOs":118},"shx","Esri Shapefile Index (SHX)",".shx is the index component of an Esri Shapefile dataset, used alongside .shp (geometry) and .dbf (attributes). You typically open it by opening the shapefile dataset (the .shp) in a GIS app rather than opening the .shx by itself.",[13,14,15,16,17],{"ext":120,"name":121,"category":7,"categoryName":8,"popularity":122,"summary":123,"howToOs":124},"kmz","KMZ (Zipped KML) geospatial archive",45,"A KMZ file is a ZIP-compressed package used to share KML map content (places, paths, overlays), often for viewing in Google Earth and other GIS tools.",[13,14,15,16,17],{"ext":126,"name":127,"category":7,"categoryName":8,"popularity":128,"summary":129,"howToOs":130},"mbtiles","MBTiles (SQLite tile set)",35,".mbtiles is a single-file map tile package used to store tiled maps (raster or vector tiles) in a SQLite database. It’s commonly opened in GIS and mapping tools such as QGIS, GDAL-based tools, and MapTiler Desktop.",[13,14,15,16,17],[132,135,138],{"label":133,"to":134},"Home","/",{"label":136,"to":137},"File Extension Index","/file-extension",{"label":139,"to":140},".PRJ","/file-extension/prj","category-gis","/category/gis","Learn what .PRJ files are, how to open them on every platform, common fixes, and security best practices.",[13,14,15,16,17],[146,149,152,155,158],{"os":13,"label":147,"to":148},"Open .PRJ on Windows","/how-to/open-prj-on-windows",{"os":14,"label":150,"to":151},"Open .PRJ on Mac","/how-to/open-prj-on-mac",{"os":15,"label":153,"to":154},"Open .PRJ on Linux","/how-to/open-prj-on-linux",{"os":16,"label":156,"to":157},"Open .PRJ on iOS","/how-to/open-prj-on-ios",{"os":17,"label":159,"to":160},"Open .PRJ on Android","/how-to/open-prj-on-android",[54,60,66],[57,58],[],"untrusted_source",[166,170],{"name":167,"description":168,"affiliateUrl":169},"Avast","Avast offers free and premium antivirus software that protects against viruses, malware, ransomware, and phishing. Scan files before opening them to ensure safety.","https://www.avast.com/lp-aff-consumer-store?expid=inf601",{"name":171,"description":172,"affiliateUrl":173},"Norton","Norton 360 delivers comprehensive antivirus protection, VPN, and identity theft monitoring. Scan files for threats before opening to keep your device secure.","http://buy.norton.com/aff_home?utm_campaign=en-ww_nor_n36_aff_nas_nau_nah_cj_nad_low:_sec_nat_mktc_norton_360"]