Your comment brought up a good point, so I ran some more tests with ints. http://bouncybouncy.net/ramblings/posts/json_vs_thrift_and_protocol_buffers_round_2/

Your comment brought up a good point, so I ran some more tests with ints. http://bouncybouncy.net/ramblings/posts/json_vs_thrift_and_protocol_buffers_round_2/ http://bouncybouncy.net/ramblings/posts/json_vs_thrift_and_p... Protocol buffers won hands down as far as space used... The speed issues are still there, but I'm sure that over time things will improve. If the C extension for simplejson can speed up serialization by an order of magnitude, I have no doubt that similar improvements can be made to protocol buffers and thrift.