Ambra — read comfortably, look deeper

Ambra brings a personal EPUB library and an integrated EPUB Inspector to Chrome. For readers, it is a place to make books your own: adjust the reading experience, find passages, and keep your notes. For EPUB authors and publishers, it connects the book you see with the files behind it—making investigation and debugging easier without leaving the reader.

Here to explore how a book is built? Meet the EPUB Inspector: source and content inspection, reading-to-source navigation, and reference finding in one place.

Reading with a screen reader? For continuous reading in a reflowable book, consider scrolling mode: Alt+Shift+Page Down (Option+Shift+Page Down on Mac). Return to pagination: Alt+Shift+Page Up (Option+Shift+Page Up on Mac).

Mac laptops may require Fn+Down/Up for Page Down/Up, together with the other shortcut keys. These commands select a mode rather than toggle it and preserve your reading position. Fixed-layout books keep their fixed layout.

Choose whichever mode works for you. Screen-reader support is still being tested; feedback about your reading experience is welcome.

More room for reading

A library on your device. Import saved EPUBs, keep books together, and return to your saved reading position.
A reading style that suits you. Adjust text and reader themes, and choose pagination or scrolling for reflowable books. Fixed-layout books retain the publisher’s page design.
Read wide tables without changing the page. Use Expand table to open a separate table viewer with zoom and two-way scrolling.
Find your way. Use the table of contents, book search, reading-position control, and bookmarks to reach the passages that matter.
Keep your thinking alongside the text. Highlight passages, add notes, and revisit them with your bookmarks.
Listen when the book includes narration. Play embedded recorded narration with synchronized text highlighting; this depends on the EPUB’s supplied narration, not automatic text-to-speech.

Book details gives the description its own section, with rights and accessibility information under Publication details. Show more reveals a longer, still bounded excerpt; an ellipsis means text was omitted. Descriptions retain at most two paragraphs (700 characters initially, 1,400 expanded); rights statements are capped at 140 characters initially and 600 expanded. These are excerpts, not interpretations of legal terms. EPUB Inspector retains the original metadata.

Page theme is in Settings, between Reader theme and Brightness, and applies across books. Its flyout offers three vertically listed samples for White, Sepia, and Dark, with a check beside the selected sample. For reflowable content, these control the page background and base text/link colors, even when a publisher specifies its own page colors. Deliberately colored passages and illustrations retain their own styling. The Book default font choice still preserves publisher typography, and fixed-layout artwork is never recolored. Previously saved per-book page themes are no longer used; an existing legacy default page theme becomes the global choice, otherwise the default is White.

Always show one page, in the book’s Page menu, keeps reflowable paginated content on one centered page instead of a two-page spread. Its switch is below Page width. This choice is saved per book and is off by default. It also applies to reflowable sections in mixed-layout books; fixed-layout pages are unchanged. Scrolling is unchanged and already uses a centered, width-limited reading area.

Settings uses consistent flyout rows for Reader theme, Page theme, Reading mode, Page turn, and Language, with their current values shown beside their names. The appearance section starts with Reader theme, followed by Page theme, then the directly accessible Brightness slider. Page-theme samples and reading-mode keyboard shortcuts are shown inside their respective flyouts. Language and Help & About remain together at the bottom. Book options and Ambra settings share the same title styling. Arrow keys move between choices, Enter or Space selects one, and Escape returns from a flyout to its parent.

Bookmarks on the progress bar appear as small blue ribbons once book-wide pagination is ready. They update when text size or window size changes, and mirror for right-to-left books. The bar keeps its usual click, drag, and keyboard controls; use Bookmarks and highlights to browse saved bookmarks by name.

Keyboard focus on the reading-position scrubber is shown by a ring around its thumb, not a box across the labels and track. Mouse and touch dragging retain focus without displaying the keyboard ring; using the keyboard brings it back.

Return after a reading jump

Use Chrome’s Back and Forward buttons to revisit reading locations. Ambra remembers completed jumps from the contents, chapter navigation, search, bookmarks, highlights, notes, in-book links, Go to page/percentage, and a released reading-position drag. There are no extra history buttons in the reader.

Ordinary page turns and scrolling update the current stop rather than adding stops. For example, jump from A to B, then read on to C: Back returns to A and Forward returns to C. A new jump after Back replaces the forward branch. Text-size and layout changes, cancelled or unsuccessful jumps, and popup footnotes do not add stops.

Locations follow the book’s content, not old page numbers, and the current reading-history stack survives a page refresh. Library and other real pages remain ordinary browser navigation. Closing the tab ends this tab’s history; your saved reading progress and bookmarks remain separate.

Take your annotations with you

Bookmarks use the same compact card treatment as highlights. Chapter titles wrap to two lines; hover a title to read it in full. A separate page badge stays visible even when the title is long. Its number is the bookwide page in your current layout, so it updates when you change text size or page width. Finding page… means pagination is still being measured; Page unavailable is shown in scrolling mode or when the saved position cannot be placed. Existing saved labels and locations are not rewritten. Publisher bookmarks keep their Publisher note tag and cannot be deleted.

Use the card title to return to its saved position. After keyboard deletion, focus moves to the next bookmark, or the previous one if the last card was removed; removing the final bookmark leaves focus in the empty Bookmarks tab.

While using an inline highlight, selection, or footnote popup, moving over its controls does not summon the reader toolbar or progress bar over it—even near the screen edges. Typing in a note stays in the note editor. Moving to a reading edge outside popup controls or focusing the reader toolbar still reveals the usual controls; Escape keeps its existing popup-dismissal behavior. Page note icons stay beneath overlapping popups, including when a note editor is shifted down to fit near the top of the screen.

EPUB annotation export and import let you back up or share your reading work separately from the book. Ambra exports your highlights, text notes, bookmarks, and bookmark labels as an EPUB Annotations 1.0 JSON file (… - annotations.json), and imports compatible JSON into the open book.

Use the same book or edition for best results. Ambra skips unsupported locations and detected duplicates. Imported highlights use yellow, and compatibility varies between annotation tools.

The Export button uses a downward download arrow; Import uses an upward upload arrow.

Adding a downloaded book

An empty library offers two choices: Bring a book → Choose EPUB files… opens the file picker for EPUBs on your device; Find your next book → Explore free books reveals trusted sources below the choices. The cards stack in a narrow popup. Settings, Help, and the popup’s expand control remain in the header; Import EPUB and Sort appear after your first book is added. You can still explore sources through Find books in a populated library.

For beautifully formatted classics, try Standard Ebooks and choose Advanced epub on a book’s page. Project Gutenberg offers a vast collection; choose an EPUB or EPUB3 download. For read-along audio, ReadBeyond offers EPUBs with recorded narration; choose Download, not the browser-based Read+Listen. Source links open in a new tab. Check the book’s license and your local copyright rules.

When a supported EPUB download opens Ambra, keep that library tab open while the book downloads, is prepared for reading, and is added to your library. The status changes to a checkmark and the EPUB’s title after the book has been saved and the library refreshed. Choose Read now to open it, or Dismiss to clear finished messages without interrupting other imports.

In an empty library, the welcome choices are hidden while a book is being added so the progress stays in focus. They return if the import fails or is cancelled and the library is still empty.

Open Library tabs update automatically when a book finishes importing or is deleted in another tab. Each tab keeps its own download status and display choices; no manual reload is needed.

If a file is not a valid EPUB, Ambra says so in the error headline. Smaller technical details remain visible underneath for troubleshooting. Library error cards are centered and use the same maximum width as download notifications.

While the status says Downloading, choose Cancel download to stop Ambra’s download and cancel the paused original download in Chrome. Cancellation is no longer available once preparation or saving starts, and does not apply to files chosen from your device. If Ambra cannot confirm cancellation, its error message directs you to Chrome Downloads to check and cancel the original download.

If automatic import fails, follow the error message and use Choose EPUB files… (or Import EPUB in a populated library) to select the downloaded file. Ambra leaves the original browser download available unless a successful import has been confirmed or you explicitly cancel it.

Keyboard shortcuts and help, close at hand

Open Settings → Help & About or the Help & About footer in Book details without leaving your book. The library also has Help & About. Mod+/ opens the shortcut popup; Mod means Command on Mac and Control elsewhere.

Some useful defaults:

Mod+F: search the book. Mod+B: toggle a bookmark.
Mod+G: go to a page. Mod+Shift+G: go to a percentage.
Page Down / Page Up: next / previous page in pagination.
Space / Shift+Space: next / previous page in pagination. In scrolling mode, Page keys and Space retain native scrolling.
Left / Right: navigate in the physical direction, following the book’s reading direction, including right-to-left books; in scrolling mode, move between sections.
Alt+Page Up / Alt+Page Down: previous / next section—a reading-order file (spine item), not necessarily a table-of-contents chapter.
Escape: dismiss a dialog and return focus to its opening control.

The shortcut popup is a quick reference showing the default shortcuts for your current platform. A single Enable keyboard shortcuts checkbox lets you turn Ambra’s shortcuts on or off globally. This preference stays local and is shared across Ambra tabs in the same browser profile. Browser or assistive-technology shortcuts may take priority; visible controls remain available.

Go to opens a small numeric dialog, not a toolbar menu or a Book details control. Focus the book or a reader toolbar button before using the shortcut. Enter submits a valid whole number; Escape dismisses and returns to reading. Pages range from 1 to the measured book-wide page count, and remain unavailable while that count is being measured. Percentages range from 1 to 100 and use the progress bar’s existing seek behavior (coarse section-based positioning until pagination is ready). Both require reflowable pagination: scrolling and fixed-layout content show an explanation instead of silently doing nothing or changing reading mode. Editing, text selections, widgets, and other dialogs keep their own keyboard ownership.

Reading tips

Turn from the outer margins. Click to the right of the rightmost page’s reading area to move right, or to the left of the leftmost page’s reading area to move left (reversed reading order in right-to-left books). Reflowable content and whitespace inside its reading area do not turn pages. Fixed-layout books also accept taps within the outermost 8% of each rendered outer page, capped at 64 screen pixels, so artwork filling the width remains navigable. The gap between pages and their inner edges never turn pages. Links, controls, editing, and text selection keep their own behavior.
A quiet welcome. The first book you successfully open offers a short illustrated introduction to turning pages and returning to your Library. Choose the centered Start reading button, close it, or press Escape to continue at the same position. Dismissing it saves a versioned acknowledgement for this browser profile, across books; it does not change your reading settings. To return to your books, click or tap the library icon in the reader toolbar. You can revisit Reading tips in the reader’s Help & About at any time. Its in-app actions, Reading tips and Show keyboard shortcuts, appear as separate button rows; User guide is a separate external link. Tips follow the current book’s reading direction and paginated/scroll layout; keyboard tips appear only when shortcuts are enabled. Loading or failed book opens do not count as a first reading. If browser storage fails, reading remains available, but the welcome may appear again next time.
Settle back into the book. When reader controls are showing, a page-turning click or tap first dismisses them without turning the page. The next click turns normally. Pinned panels stay open; links, images, and deliberate swipes retain their own behavior.
Choose your rhythm. Pagination turns pages; scrolling keeps Page Up, Page Down, and Space available for native scrolling. For continuous screen-reader reading, consider scrolling using the shortcut above. Mode selection is reflowable-only; choosing the current mode leaves it unchanged.
Keep keys in context. Reading navigation belongs to the book content; modified commands such as search, bookmark, and the shortcut popup can also work from toolbar buttons. Text fields, selections, interactive widgets, and dialogs retain their own keys. Ambra does not require a screen reader’s application mode.
On a Mac laptop. Page Up/Down may need Fn+Up/Down. Section navigation then uses Option+Fn+Up/Down; add Shift to select pagination or scrolling respectively. A section is a spine item, not necessarily a named chapter, and the default Left/Right navigation follows the book’s reading direction.

Book handling and library storage stay in your browser profile, without a cloud library or automatic cross-device library sync. Keep original EPUBs and annotation exports as backups: storage has limits, and removing the extension, clearing its data, or losing the profile can remove local books and reading data.

To copy an EPUB out of your library, open that book’s Book details → Publication details in the Library or reader and choose Save as… near File name. Chrome asks where to save the original EPUB, using its imported filename. Keep that Library or reader tab open until you confirm the save dialog and the download starts. This copies the bytes already stored on your device without downloading the book again or changing the library copy, reading position, or annotations. Canceling the save dialog leaves everything unchanged.

Feedback is welcome through GitHub issues or AmbraEPUB@outlook.com—email needs no GitHub account. Reader diagnostics may include book details, paths, reading positions, and recent actions. Review them before sharing; nothing is sent automatically. GitHub issues are public.

Diagnostics keep the latest 500 events in memory and reset when the reader reloads. They include panel/menu opening, closing and pinning, navigation sources, and setting changes with before/after values. Requested actions are distinguished from completed layout/load events. Entries are capped at 512 characters, and copied context is bounded too. New interaction events omit search queries, annotation text, and link URLs; existing error details can still contain book paths, so review the copied report before sending it.

Ambra is in beta; its planned unlisted extension-store release is not yet published. Visit the public, MIT-licensed repository for source and beta context, and the canonical privacy policy for privacy details.