This PDF to Text is a free and powerful utility that can be used to convert PDF documents to editable text files. 
This app only works locally without going through the server. It allows you to extract texts instantly, real-time.
You don't need to upload PDFs to any server. It's very safe, and guarantees privacy. 

You can also extract text from many PDF files with one click. You can select PDF files to extract from your local computer and from Google Drive directly.

Save bulk extracted text files:
Compress each extracted file
Merge each extracted file into one text