Readwise Reader + EPUB: Better Highlighting for PDFs Converted to EPUB
Readwise Reader is a read-it-later app that highlights, annotates, and reviews your reading — books, articles, PDFs, and EPUBs all in one place. It supports both PDF and EPUB uploads. But for most documents that started as PDFs — research papers, reports, ebooks — converting to EPUB first gives you better highlights, cleaner text, and more useful AI summaries.
What is Readwise Reader?
Readwise Reader is an all-in-one reading and annotation tool by the team behind Readwise (the spaced repetition app for book highlights). Reader features:
- Upload PDFs, EPUBs, web articles, newsletters, Twitter/X threads, and YouTube videos
- Highlight and annotate anything — syncs back to Readwise for daily review
- Ghostreader: AI-powered summaries, key points, questions, and explanations
- Mobile apps (iOS, Android), web app, and browser extension
- Text-to-speech for hands-free listening
Reader is particularly popular with academics, knowledge workers, and researchers who read large volumes of long-form content.
Why EPUB is better than PDF in Readwise Reader
Readwise Reader handles both formats, but EPUB has meaningful advantages for most documents:
| Feature | PDF in Reader | EPUB in Reader |
|---|---|---|
| Text highlighting | Works but tied to page layout | Clean paragraph-level highlights |
| Font size control | No — fixed page size | Yes — text reflows |
| Ghostreader AI quality | Good (on clean PDFs) | Better — cleaner text extraction |
| Chapter navigation | Page numbers only | Full table of contents |
| Mobile reading | Zoom required on phone | Reads naturally at any screen size |
| Text-to-speech | Works (may stumble on columns) | Smooth, paragraph-by-paragraph |
For PDFs that are just scanned images (rather than text-based), the PDF version in Reader won't support highlighting at all. Converting to EPUB with OCR solves this.
Step-by-step: PDF → EPUB → Readwise Reader
- Convert the PDF: Go to pdf2epub.toolkit.bot, upload your PDF, download the EPUB (takes ~30 seconds)
- Upload to Reader: Open read.readwise.io, click the + button → Upload → select the EPUB file
- Read and highlight: Open the document in Reader. Use standard highlighting (click and drag text). Add notes with the note icon.
- Review highlights: Highlights sync to Readwise automatically. Open Readwise for spaced repetition review of your highlights.
- Use Ghostreader: In any document, tap the ghost icon for AI summary, key points, or to ask questions about the content.
Frequently asked questions
Does Readwise Reader support EPUB files?
Yes — Readwise Reader fully supports EPUB uploads. You can drag and drop an EPUB into Reader or upload it via the web interface. EPUBs display with proper chapter navigation, reflowable text, font size control, and full highlight/note support. Reader also syncs highlights to Readwise for spaced repetition review.
Why convert a PDF to EPUB before uploading to Readwise Reader?
Readwise Reader can open PDFs directly, but PDF highlighting in Reader has limitations: highlights are tied to fixed page coordinates, paragraphs don't reflow if you change font size, and Reader's AI summary works better on clean reflowable text than on PDF text extraction. Converting to EPUB first gives Reader cleaner paragraph structure, which improves highlight quality and AI-generated summaries.
Does Readwise Reader's AI summary work better with EPUB than PDF?
Generally yes. Reader's 'Ghostreader' AI features (summary, key points, questions) work by reading the document text. PDFs sometimes have extraction artifacts — ligature issues, column-order problems, running headers repeated in the text. EPUB text is clean and sequential. On complex academic PDFs, converting to EPUB first can meaningfully improve Ghostreader output quality.
Can I import EPUB files into Readwise Reader on mobile?
Yes. On the Readwise Reader iOS or Android app, tap the + button → Upload → select your EPUB file. Alternatively, use the web interface at read.readwise.io and upload there — it syncs to all your devices. Highlights and notes sync across devices and back to Readwise for review.
How does Readwise Reader compare to Kindle or Kobo for reading research EPUBs?
Readwise Reader and Kindle/Kobo serve different purposes. Reader is best when you want to highlight, take notes, and review them later via spaced repetition — it's a reading workflow tool. Kindle and Kobo are better for distraction-free reading without active annotation — ideal for the initial read-through. Many researchers use both: read the EPUB passively on Kindle first, then re-read and annotate in Readwise Reader.