A developer might have lost their original unencoded files and only has the encoded version left on their server.

Upgrading PHP versions sometimes requires re-encoding scripts, which is impossible without the original source. How Online Decoders Work

If you ignore the warnings and upload your encoded file to a random "free online ionCube decoder," here is what typically happens:

Many online "decoders" are unreliable, may charge per file, or could potentially bundle malware. Open Source Projects: Repositories on ioncube-decoder

If your goal is simply to run the code, you don't need a decoder. You just need the ionCube Loader , which is a free PHP extension that executes the bytecode on your server.