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Look Up EPSG Codes From Well-Known-Text (WKT) / prj Files With Prj2EPSG

OpenGeo announces Prj2EPSG, a free online service that can look up the EPSG (European Petroleum Study Group) code for a coordinate system based on:

  • A WKT (Well-Known Text) description. e,g, copying and pasting WKT text into the box:


yields the EPSG code 4326.

  • A .prj file, often found with shapefiles or other geographic data files to define the coordinate system; select the prj file to upload, and get back the original prj data in the box and the EPSG code:


  • Type in keywords and get back a list of possible choices:


  • Or just type in the EPSG code, and get back a data page with the coordinate system defined, and the WKT listed.

Click on any of the code links in the search results to get a full data page:


It’s kind of picky about how you describe the data, and not necessarily in a consistent fashion. For example, enter “NAD 27” and you’ll get no results, but enter “NAD27” and you’ll get results; enter “WGS84” and no results will come up, while “WGS 84” yields lots of results. Only the top 20 results display, and that’s not always enough to find what you’re looking for; there’s no option to move on to another page of results, or change the total number of results displayed. Plus, partial matches aren’t allowed; entering “SWEREF” or “SWEREF 99” yields no results, you have to specify “SWEREF99”. So for now it’s a useful adjunct to, but not yet a replacement for, the Spatial Reference website that also allows searching of the EPSG code database with keywords, and which is more flexible in matching terms (e.g. it will find just “SWEREF”). But unlike Spatial Reference, Prj2EPSG has a web service interface that allows basic search queries.

Via SlashGeo.

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