We introduce PDFMEF, a multi-entity knowledge extraction framework for scholarly documents in the PDF format. It is implemented with a framework that encapsulates open-source extraction tools. Currently, it leverages PDFBox and TET for full text extraction, the scholarly document filter described in  for document classification, GROBID for header extraction, ParsCit for citation extraction, PDFFigures for figure and table extraction, and algorithm extraction . While it can be run as a whole, the extraction tool in each module is highly customizable. Users can substitute default extractors with other extraction tools they prefer by writing a thin wrapper to implement the abstracts. The framework is designed to be scalable and is capable of running in parallel using a multi-processing technique in Python. Experiments indicate that the system with default setups is CPU bounded, and leaves a small footprint in the memory, which makes it best to run on a multi-core machine. The best performance using a dedicated server of 16 cores takes 1.3 seconds on average to process one PDF document. It is used to index extracted information and help users to quickly locate relevant results in published scholarly documents and to efficiently construct a large knowledge base in order to build a semantic scholarly search engine. Part of it is running on CiteSeerX digital library search engine.