Memory copy speed is known to be a significant barrier to high-speed communication. We perform an analysis of the requirements for a copy-free buffer system, develop an implementation-independent applications programming interface (API) based on those requirements, and then implement a system that conforms to the API. In addition, we design and implement a fully copy-free file system cache. Performance tests indicate that our system dramatically outperforms traditional systems on communications-oriented tasks by a factor of 2 to 10. Application programs that have been modified to utilize our copy-free system have also shown reductions in run time, ranging from 10% to nearly 50%.