This is a follow-up on my experimentation with PHP compilers.  After trying Bcompiler and choosing not to use Zend Guard, I tried out Source Guardian.  It will compile PHP into byte codes for either PHP 4 or PHP5 using a command line executable (or a GUI in Windows).  The PHP file is encoded in place and can be used just as if it wasn’t encoded at all.  You only need to copy a directory of dynamic php extensions into a parent folder of the script (e.g. the web server’s document root would work fine) which are used to decode and run the encoded script.

I tried this out and it worked flawlessly.  Not only that, but this product opens doors to add limited licensing to your products.  You can, for example, set an expiry date on code, or stipulate that the code can only be run on a certain IP or MAC address.

All I can say is that I will definitely be purchasing this product and I recommend it for anyone who distributes PHP source code and doesn’t want to give away all intellectual property.