Free PDF Compressor
Full user review
"Disaster - do not use!"
Does not recognise 1.6, and, if you run it, it corrupts the original file completely.
I had a 10 Mb file that I tried this on. First, it gave an error, saying it did recognise pdf 1.6. When I tried again, it reported that it was successful. But, file size was now only 1 KB, and corrupted. Thank goodness I had made a copy of my file.