libcapnp-dev 0.5.3-2ubuntu1.1 (amd64 binary) in ubuntu xenial

 Similar to Protocol Buffers, Cap'n Proto is an efficient means of
 serializing structured data to be transferred across a network or
 written to disk. Users write a Cap'n Proto definition file that
 drives a code generator, which in turn emits C++ code for encoding &
 decoding messages in the Cap'n Proto format.
 .
 In addition to being extremely fast, Cap'n Proto also smooths over some
 of the rougher aspects of Protocol Buffers & introduces a number of new
 features to boot.
 .
 This package contains the headers and static libraries needed for writing
 C++ applications.