To cite OpenCPU in publications use:

Jeroen Ooms (2013). The OpenCPU System: Towards a Universal Interface for Scientific Computing through Separation of Concerns arXiv:1406.4806 [stat.CO] URL http://arxiv.org/abs/1406.4806.

Corresponding BibTeX entry:

  @Article{,
    title = {The OpenCPU System: Towards a Universal Interface for
      Scientific Computing through Separation of Concerns},
    author = {Jeroen Ooms},
    journal = {arXiv:1406.4806 [stat.CO]},
    year = {2014},
    url = {http://arxiv.org/abs/1406.4806},
  }