OpenPDF is an open-source Java library for creating, editing, rendering, and encrypting PDF documents, as well as generating PDFs from HTML. It is licensed under the LGPL and MPL open source licenses.
Update: Tigramite now has a new CausalEffects class that allows to estimate (conditional) causal effects and mediation based on assuming a causal graph. Have a look at the tutorial. Further, Tigramite ...