toms917, a C code which evaluates Wright's Omega function, by Piers Lawrence, Robert Corless, David Jeffrey.
The text of many ACM TOMS algorithms is available online through ACM: https://calgo.acm.org/ or NETLIB: https://www.netlib.org/toms/index.html.
The computer code and data files made available on this web page are distributed under the MIT license
toms917 is available in a C version and a C++ version.
TOMS443, a C code which evaluates Lambert's W function. This is a version of ACM TOMS algorithm 443.
TOMS743, a C code which evaluates Lambert's W function. This is a version of ACM TOMS algorithm 743, by Barry, Barry and Culligan-Hensley.
Piers Lawrence, Robert Corless, David Jeffrey.