Chat with your PDFs offline: document AI that never uploads a file

How to ask questions about PDF documents on Android without uploading them anywhere - on-device retrieval-augmented generation explained simply.

The problem with cloud document AI

Uploading a contract, medical record or unpublished manuscript to a cloud AI means handing it to a third party. For lawyers, researchers, students and anyone with sensitive files, that is a real privacy cost. On-device document AI removes the upload step entirely.

How on-device PDF chat works

The app parses your PDF locally, splits it into chunks, and builds a vector index stored on the phone. When you ask a question, retrieval finds the relevant passages and a local language model writes an answer grounded in your document. The technique is called RAG - retrieval-augmented generation - and the whole pipeline runs without a network connection.

Where to get it

Offline AI Expert is a free Android app built around this idea: load a PDF, ask questions, get cited answers. It uses a native inference engine with on-device vector search, so contracts, manuals and study notes stay on the phone where they belong.