Download of Cogo 2.1 was on the developer's website when we last checked. We cannot confirm if there is a free download of this software available. This free software is a product of Mountaineer Consulting inc. The program lies within Education Tools, more precisely Science Tools.
COGO.exe is the frequent file name to indicate this program's installer. According to the results of the Google Safe Browsing check, the developer's site is safe. Despite this, we recommend checking the downloaded files with any free antivirus software. The most popular versions among Cogo users are 2.1 and 1.3.
From the developer:
CoGO! is a Coordinate Geometry tool of particular value to those involved in 2D mapping of land parcels, properties and the like. It allows the sequences of lines and arcs that form the outline of a land feature to be specified in terms of lengths and bearings and provides graphical verification of those sequences.
You may want to check out more software, such as Colorado DOT COGO, CMT CogoCAD Pro or "Sight" Survey, which might be related to Cogo.