I’ve got a small list of COBOL resources which I’m slowly going to share over the next few days, and then I’ll compile them all into a megathread! Here’s some FLOSS to get us started.

GnuCOBOL, originally known as OpenCOBOL, was designed by Keisuke Nishida. It was first released in 2002. In 2013, OpenCOBOL was accepted as a GNU Project and was eventually renamed to GnuCOBOL.

The compiler is written in C, with a C++ branch. To contribute to the project, see their SourceForce project page.