Themida is described as 'Advanced Windows software protection system, developed for software developers who wish to protect their applications against advanced reverse engineering and software cracking'. There are more than 10 alternatives to Themida for a variety of platforms, including Windows, Linux, Mac, Online / Web-based and Android. The best alternative is UPX, which is both free and Open Source. Other great apps like Themida are VMProtect (Paid), Appetize.io (Freemium), PELock (Paid) and FUPX (Free).
UPX (Ultimate Packer for eXecutables) achieves an excellent compression ratio and offers very fast decompression. Your executables suffer no memory overhead or other drawbacks for most of the formats supported, because of in-place decompression.
No screenshots yet
UPX vs Themida opinions
This alternative is disputed. UPX is still a legitimate alternative to Themida, but it might have issues that some users think are important.
VMProtect Ultimate - All-In-One Solution For Software Licensing And Protection. VMProtect protects code by executing it on a virtual machine with non-standard architecture that makes it extremely difficult to analyze and crack the software.
ASPack makes Windows programs and libraries smaller up to 70% (the compression ratio is higher than the ZIP standard by 10-20%), and decrease load times across networks, and download times from the internet.