I need to send some data but this should be done compressed using gzip or deflate algorithms (like in http). I have been searching for some info about the possibility of doing it on this model and for pure c libraries available that would fit.
I'm not aware of any libraries that have been tested with the nRF51 series, but maybe some of the community users can help you!
I found a thread on stackoverflow that might be of interest, and also this library seems to meet your requirements, if you can get it running on the nRF51.
How much RAM do you have available?
256KB of RAM, i will have a look to those libs, thanks!!