We present JASSjr, a minimalistic trec_eval compatible BM25-ranking search engine that can index small TREC data sets such as the Wall Street Journal collection. We do this for several reasons. First, to demonstrate how a term-at-a-time (TAAT) search engine works. Second, to demonstrate that a straightforward and competitive search engine with indexer can be written in under 600 lines of documented code. Third, as a way of providing a simple code-base for teaching Information Retrieval. We present two index-compatible versions (one in C/C++, the other in Java) that compile and run on MacOS, Linux, and Windows.