rtf-grimoire is a Rich Text Format (RTF) document tokenizer, intended to enable the creation of full RTF parsers.
It was written based on the RTF Specification, which unfortunately comes under an unfriendly license that doesn't allow redistribution, but may be freely downloaded from Microsoft.
An example parser based on rtf-grimoire may be found on [my github] (https://github.com/compenguy/rtf2text). It has been tested with a wide range of rtf files from a variety of text editors with great success so far.