Harbour Compiler
This is the current official Github repo to download the Harbour compiler from.
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 It is strongly encouraged that you use the Main Repo, since this one is no longer maintained.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
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
A collection of small console and web apps to help you start your journey in developing with Harbour on Windows and Linux (Not tested on Mac).
All the samples require the use of VSCODE. 

Please review the following articles:

Harbour Core Development
Useful information if you want to create C level contribs or add to the harbour compiler.

C (The Language)
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.

Currently the most active site to communicate with Harbour core contributors.!forum/harbour-users
Currently the most active site to ask questions about Harbour.

Older Reference Material

3rd Party Tools

3rd Party Vendors