ChatDOC answers questions about uploaded PDFs and shows the source passage behind each answer. Around it sits a wider family: a standalone PDF parser API, ChatPaper for academic reading, browser extensions and a studio product.
Citing the source is what makes this category usable rather than merely impressive, and it is precisely where most chat-with-PDF tools fail. An answer drawn from a hundred-page contract or a research paper is worthless if you cannot check it, because verifying it manually costs more than reading the section yourself would have. The parse-chat-verify loop treats the citation as part of the answer rather than an optional extra.
Selling the parser separately as an API is a good sign about where the engineering effort went – document parsing is the unglamorous foundation that determines whether anything above it works, particularly on tables, multi-column layouts and scans. The remaining caution is ordinary: a cited passage proves where an answer came from, not that the answer interpreted it correctly, so read the source for anything that matters.
