If the file is protected by DRM (Digital Rights Management) , these tools will not be able to read or convert the content without first removing the protection through authorized means. Getting started with WordToEPUB - The DAISY Consortium
For managing large libraries or more complex formatting, desktop applications offer more control:
If you need to automate text extraction, Python libraries like ebooklib and BeautifulSoup are highly effective for parsing the underlying HTML content.
If you want a fast, one-time conversion without installing software, several free web-based tools can handle this: : Supports direct conversion from EPUB to TXT .
: The industry standard for ebook management. You can use its "Convert books" feature to output as a .txt file.