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Reflow · Read Books Your Way

Your PDFs.Reimagined for Reading.

Turn static PDF books into a beautiful, adaptive reading experience designed around how you actually read.

  • Your original file stays untouched
  • Your fonts, your spacing, your theme
  • iPhone, iPad and Android
A fixed-layout PDF page with small two-column text, transformed into a reflowed, readable book page on a phone.
Adaptive book

Try it

Change the type. Watch the book rebuild itself.

This is the idea at the heart of Reflow. Pick a size, a typeface or a theme — the text reflows and the page count follows. Your place in the book stays exactly where it was.

Font size
Font
Theme
Original PDF
280pages
Reading pages
280
Your place
29%
Page counts in this demo are illustrative. In the app, Reflow measures the real layout on your device.

The problem

PDFs Were Never Designed for Reading on Every Screen.

PDFs preserve pages beautifully. That is exactly what they were made for — and why a page designed for paper rarely fits the screen in your hand.
A printed page, shrunk to a phone
The same page, rebuilt to read
  • Fixed page layouts

    Every page is frozen at its printed size, whatever device you open it on.

  • Tiny text on phones

    A letter-sized page shrunk to a phone turns body text into fine print.

  • Endless zooming

    Pinch, pan, re-centre, repeat — reading becomes navigation.

  • Awkward columns

    Two-column layouts force you to scroll down, up and across for every page.

  • Broken reading flow

    Sentences split across pages, headers and footnotes interrupt every few lines.

  • Typography you can’t change

    The font, size and spacing were chosen for paper — not for your eyes.

  • Hard to navigate

    Without real structure, finding a chapter means scrubbing through pages.

  • One screen size

    The layout is right for one size of paper, and approximately wrong for everything else.

None of this is a flaw in PDF. It is a format for preserving documents. We simply think reading deserves its own format.

The idea

Meet a Better Way to Read.

Reflow extracts the content of your PDF, works out how it is organised, and rebuilds it as a responsive book — one that reflows to fit your screen and your preferences.
  1. 01

    PDF

    The file you already have.

  2. 02

    Understand

    Text, headings, chapters, images and reading order are identified — with OCR for scanned pages.

  3. 03

    Rebuild

    The content is reassembled as a structured, reflowable book.

  4. 04

    Read

    Typography and layout adapt to you and your device.

Not another PDF viewer.

A viewer shows you the page. Reflow rebuilds the book.

Traditional PDF reader

  1. PDF
  2. Fixed layout
  3. Zoom
  4. Scroll

Reflow

  1. PDF
  2. Understands content
  3. Rebuilds structure
  4. Adaptive layout
  5. Personalised reading

Same book. Better reading.

The app

See Reflow in action.

Real screens from Reflow on Android — the same book, rebuilt for reading.
  • Reflow reading view: a chapter of the book Greedy Primates set in a large serif typeface, with page 35 of about 281 and 19% of chapter shown at the bottom.
    The reading viewClean typography, with the chapter, page and progress quietly at the edges.
  • Reflow reader settings sheet with Light, Sepia, Dark and Black themes, Literata, Gelasio, Inter and Atkinson typefaces, and sliders for font size, line spacing and paragraph spacing.
    Reader settingsTheme, typeface, size, line and paragraph spacing, margins — the book reflows as you go.
  • Reflow table of contents drawer for Greedy Primates, listing chapters with their sections — such as The Three-Pound Universe and The Ancestral Environment — and page numbers.
    A real table of contentsChapters and sections recovered from the PDF, with page numbers in your current layout.
  • Reflow book details screen for Greedy Primates by Prabhasudhan: the cover, 11% complete with 1 hour 4 minutes left, a Continue Reading button, 30 chapters, 85 PDF pages, 1 hour 12 minutes to read, and a short description.
    Your book, at a glanceProgress, time left, chapters, PDF pages and a description — and one tap to continue where you stopped.
  • Reflow reader menu listing Bookmarks, Highlights, Notes, Ask the book, Download for offline and About this book.
    Everything in one placeBookmarks, highlights, notes, Ask the book and offline download from the reader menu.
  • Reflow Ask the book screen with the request "Summarize this chapter" and a summary of the chapter below it, with numbered citations to the passages it draws on.
    Ask the bookSummaries and answers drawn from the book you are reading, with citations.

How it works

From file to book in four steps.

  1. Step 1

    Import Your PDF

    Bring the books you already own.

  2. Step 2

    We Rebuild the Book

    The content is analyzed and structured into chapters, sections, paragraphs, images and more.

  3. Step 3

    Make It Yours

    Choose the typography, spacing, theme and layout you prefer.

  4. Step 4

    Just Read

    Your book automatically adapts to your screen and preferences.

Adaptive reading

Your Book Should Adapt to You.

Your screen changes. Your preferences change. Your book should adapt.

The original PDF layout doesn’t dictate how you read. Adjust anything below and the same chapter is set again — for a phone, a tablet or a large screen.

Reading settings

Font
Theme
18px
1.60
62 ch

Reading pages on this device

301

Original PDF: 280 pages · illustrative

Dynamic pagination

Pages That Fit Your Reading.

A traditional PDF has a fixed number of pages. Reflow creates its own reading pages by measuring how your book is actually laid out on your screen.

Reading pages are calculated from

  • Font
  • Font size
  • Screen dimensions
  • Margins
  • Line spacing
  • Paragraph spacing
  • Images
  • Layout

Chapters you have opened get exact page numbers straight away; the rest start as a calibrated estimate (shown as ~281) and are refined in the background.

Reading pages are a way of presenting the book on your screen. Your original PDF — and its page numbers — are never modified.

16px280reading pages
20px318reading pages
24px367reading pages

Document understanding

A book, not a stack of pages.

Instead of treating your book as a stack of pages, the reader understands its content: which lines are headings, where a chapter begins, what is a quotation, which image belongs to which paragraph.
  • Chapters and sections become a real table of contents.
  • Paragraphs are rejoined across page breaks.
  • Running headers and page numbers are set aside.
  • Quotes, lists, tables, footnotes and images keep their meaning.
  • Book
    • Chapter1
      • Section
      • Paragraph
      • Quote
      • Image
    • Chapter2
    • Chapter3

The reading experience

Make the page disappear. Keep the words.

Generous margins, considered typography and controls that stay out of sight until you need them. Chapter openings, quotations and images are set the way a careful book designer would set them.
  • Typography first

    Proper line lengths, real italics, balanced headings.

  • Minimal chrome

    Tap the centre of the page for controls. Tap again and they’re gone.

  • Always oriented

    Chapter, page and progress — quietly, at the edge.

Reader settings

Choose your font. Change your spacing. Make the page yours.

Every setting a careful reader might want — organised so you never have to hunt for it.
Font
16px
1.60
0.6 em

Bookmarks, highlights & notes

Mark what matters. It stays where you left it.

Annotations are attached to the underlying text, not to a page number. Change the font, the size or the device — your highlights, notes and bookmarks remain on the right words.

Next: Highlight

Reflow book details screen for Greedy Primates by Prabhasudhan: the cover, 11% complete with 1 hour 4 minutes left, a Continue Reading button, 30 chapters, 85 PDF pages, 1 hour 12 minutes to read, and a short description.

Offline reading

Read anywhere. Even at 35,000 feet.

Once a book has been processed, download it to your device from the book page or the reader menu. No continuous connection required.
  1. 01

    Download a processed book

    Keep any book from your library on your device.

  2. 02

    Read anywhere

    Highlights, notes, bookmarks and progress all work offline.

  3. 03

    Sync when you’re back

    Changes made offline are queued and synchronise automatically when you reconnect.

Reading statistics

Notice your reading life.

Gentle insights into how you read — streaks, time, pages and pace. Never leaderboards, never pressure.
Day streak
23days
Books completed
14
Reading time
62h
Pages read
4,180
Average speed
241wpm
Average session
27min
Minutes read this week285 min total
Minutes read per day this week (sample data)
DayMinutes
Mon34
Tue21
Wed48
Thu15
Fri39
Sat72
Sun56

Pages are counted as 300 words each, so they mean the same in every book and at every font size. Sample data for illustration. View daily, weekly or monthly in the app.

Intelligent assistance

Your Books Can Become More Interactive.

AI is an optional companion to reading, never a requirement. The book you read is always the author’s text — assistance appears only when you ask for it.

AI never rewrites your book. It answers questions about it.

Reflow Ask the book screen with the request "Summarize this chapter" and a summary of the chapter below it, with numbered citations to the passages it draws on.

Available now

  • Ask the Book

    Available

    Ask questions and get answers grounded in the book, with citations that open the passage they came from.

  • Explain a Passage

    Available

    Select a difficult paragraph and tap Explain for a plain-language explanation.

  • Summarize a Chapter

    Available

    Recap a chapter before you continue, or after a long break.

  • Explain Difficult Concepts

    Available

    Ask about an idea or term and get it unpacked in the context of the book.

  • Dictionary

    Available

    Select a word and tap Define to look it up without leaving the page.

Coming soon

  • Translation

    Coming soon

    Translate a word, sentence or passage without leaving the page.

  • AI Reading Assistant

    Coming soon

    A study companion for notes, review and comprehension.

Privacy & security

Your library is yours.

We built Reflow on a simple principle: your books and your reading life belong to you. Here is what that means in practice.
  • Secure account authentication

    Passwords are stored only as strong one-way hashes, and sign-in sessions use short-lived, rotating tokens.

  • Encrypted connections

    The app talks to our servers over HTTPS. Sign-in tokens are kept in your device’s secure keychain.

  • Private cloud storage

    Books are kept in private storage tied to your account; images are delivered through short-lived signed links.

  • A library you control

    Your books are private to your account — they are never shared with other readers.

  • Delete any time

    Delete a book along with its highlights, notes and bookmarks — or your whole account — right in the app.

  • Privacy-focused design

    We collect what the service needs, and explain it plainly in our Privacy Policy.

Read the details in our Privacy Policy and how to delete your data.

Who it’s for

For anyone who reads more than they’d like to zoom.

  • Students

    Course readers and textbooks you can actually study from a phone.

  • Researchers

    Long-form material with search, highlights and notes that keep their place.

  • Professionals

    Reports and industry books, readable on the commute.

  • Book lovers

    A considered reading experience for the PDFs in your collection.

  • Travel readers

    A whole library, offline, in your pocket.

  • Phone & tablet readers

    Text that is set for the screen you have — not shrunk from paper.

  • Readers with preferences

    Larger type, wider spacing, a calmer theme, Atkinson Hyperlegible or OpenDyslexic.

  • Readers of older books

    Scanned books are recognised with OCR and rebuilt as text.

FAQ

Questions, answered.

All questions
  • Reflow is a mobile reading app that turns PDF books into an adaptive reading experience. It extracts the content of your PDF, identifies its structure — chapters, sections, paragraphs, images — and rebuilds it as a book that reflows to fit your screen and your preferences.

  • No. The app creates a separate reading presentation from your PDF. The original file itself is never edited.

  • Yes — and that is intentional. Reflow measures how your book lays out with your font, size, spacing, margins and screen, and creates reading pages from that. Larger text means more reading pages. Your position in the book is preserved to the sentence, and your original PDF is not affected.

  • Yes. Download a processed book to your device and read without an internet connection — highlights, notes, bookmarks and progress all work offline and synchronise when you reconnect. Downloaded books stay on the device until you remove them or sign out.

  • Yes. Pages without a text layer are recognised with optical character recognition (OCR), then rebuilt like any other book. Results depend on scan quality.

  • Yes. Your library is private to your account. We do not sell your books or your reading data.

  • No. The text you read is the text of your book. AI answers appear separately, only when you ask, and cite the passages they draw on.

Download

Bring Your Books With You.

Reflow — your PDFs, rebuilt for reading — on iPhone, iPad and Android.

Coming soonApp StoreComing soonGoogle Play

Coming soon to iOS and Android

We’re putting the finishing touches on the store releases. Leave us a note and we’ll let you know when they’re available.

Contact us