Being a beta version, it may contain undiscovered bugs.
Addressed potential memory leaks and bugs related to improperly crafted archives. WinRAR 6.20 Beta 3 RePack / Portable
Improved speed, robust recovery tools, strong AES-128 encryption, and support for almost all archive formats. Being a beta version, it may contain undiscovered bugs
Performance improvements, especially on CPUs with eight or more threads, for better compression speeds. Being a beta version
If you are looking for specific, secure alternatives or, perhaps, a direct download, I can help you find that.
These versions usually bypass the standard 40-day shareware trial.