Links

Harbour Compiler

https://github.com/harbour/core
This is the current official Github repo to download the Harbour compiler from.
https://github.com/vszakats/harbour-core
Viktor Szakats used to be one of the most active core developers of Harbour. This is is read-only repo. It is strongly encouraged that you use the Main Repo, since this one is no longer maintained.

Harbour Info

https://harbour.github.io/
This is the "Official" web site that explains what Harbour is and who are the main contributors. This site was not maintained for a while.

Learning Harbour

Web

Harbour Core Development

http://www.fivetechsoft.com/harbour-docs/clevelapi.html
Useful information if you want to create C level contribs or add to the harbour compiler.

C (The Language)

https://en.wikibooks.org/wiki/C_Programming
Since Harbour generates native C code, and since you can also embed C code directly in your PRGs using #pragma, the following link is a great resource to learn the C language. The entire PDF version book (290 pages) can also be download from this site.

Forums

https://groups.google.com/forum/#!forum/harbour-devel
Currently the most active site to communicate with Harbour core contributors.
https://groups.google.com/forum/#!forum/harbour-users
Currently the most active site to ask questions about Harbour.

Older Reference Material

3rd Party Tools

3rd Party Vendors