Documentation

Reading should be
this simple.

OpenTheBook is a file reader, not a library. Here is everything you need — install, open, read.

01

Get started

  1. Install once. During setup, choose the file types OpenTheBook should open — PDF, EPUB, AZW3, and MOBI are all selected by default.
  2. Double-click a book. Your reading file opens directly in OpenTheBook. No import, no library, no account.
  3. Pick up where you left off. Your highlights and preferences are stored quietly on your computer.
02

Shortcuts

Reading

CtrlT
Toggle chapter sidebarShow or hide the chapter rail.
CtrlBCtrlH
Bookmarks and highlightsShow or hide saved highlights.
CtrlSCtrl.
SettingsOpen or close the settings panel.
Ctrl+Ctrl-
Text sizeIncrease or decrease text size.
Ctrl0
Reset text sizeReturn text to its default size.
Enter
FullscreenEnter distraction-free fullscreen mode when no dialog is open.
Esc
Close dialogs or exit fullscreenClose an open panel first, then exit fullscreen.
CtrlQ
Close readerClose the desktop reader window.
JKUDArrowDownArrowUpArrowLeftArrowRight
Scroll through a bookJ, D, Down, and Right move forward; K, U, Up, and Left move backward in reflowable books. D, U, Left, and Right move by a viewport; J, K, Up, and Down use the selected scroll step.

Search and help

CtrlF
Find in bookOpen the in-book search bar.
CtrlGF3Enter
Next search matchEnter applies while the search bar is focused.
CtrlShiftGShiftF3ShiftEnter
Previous search matchShift+Enter applies while the search bar is focused.
Ctrl/F1?
Shortcuts and helpOpen or close the keyboard shortcuts guide.

Use Ctrl on Windows and Linux; the same commands use Cmd on macOS. Search and navigation shortcuts apply only in their stated context.

03

Formats

PDFFixed-layout documents, rendered page by page.
EPUBReflowable books that adapt to your text size.
AZW3Kindle books, read without a Kindle app.
MOBIOlder Kindle and PocketBook files.

DRM-protected files cannot be opened. Your own, freely readable books work great.

04

Settings

  • Fullscreen — the reader opens fullscreen by default and remembers how you left it, including window size and position.
  • Display full book — read the whole book in one continuous scroll (default). Turn it off for single-chapter paging.
  • Theme — light, dark, or follow your system.
  • Text size — adjust with Ctrl + / Ctrl −, the A− / A+ buttons, or in Settings.
  • File associations — choose which formats OpenTheBook registers, then use “Open default apps” to confirm your choices.
  • Updates — signed updates are checked quietly after launch and installed when you close the reader.
05

Your data

Books stay wherever you keep them on your computer. Highlights and preferences live in a single folder, .openthebook, in your user directory. Nothing is uploaded anywhere.

06

Still stuck?

If a file still opens in another app, open OpenTheBook, go to Settings, and choose Open default apps to switch the file type over.

Questions or ideas? Write to us.

Ready when you are

Open a book.
Start reading.

Get OpenTheBook