gencoder is a simple php encoder that use base64 function algorithm to encode and decode the script.
The drawback of this script:
it doesn't have a key for encryption / decryption method.
run slower then normal php script (because it need to re-read the script and decode it).
only work on single complete php tag (one open php tag and one close php tag) because of limitation of eval function.
the encoded file will grow in double or more.
unlike Zend Encoder, this script won't solve your problem from hiding the source code from advance programmer but at least you're one step closer to making your code tougher for people to steal.