Beyond Compare is described as 'Compares files with source control integration, supports FTP and cloud storage, offers 3-way merge, and uses commands to manage syncs and differences' and is a very popular Diff Tool in the backup & sync category. There are more than 50 alternatives to Beyond Compare for a variety of platforms, including Windows, Mac, Linux, Web-based and Flathub apps. The best Beyond Compare alternative is Meld, which is both free and Open Source. Other great apps like Beyond Compare are WinMerge, KDiff3, Unison File Synchronizer and Araxis Merge.
Even if the semantic part makes it appealing, the lack of directory compare functionality combines with lack of being open-source, makes it a subpar alternative to others.