What's new
Key features
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Zen mode. A simpler reading menu with compact controls and optional session statistics. Enable it under Settings > Display > Zen mode.
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Text presets. Save and reuse your preferred font, size, thickness, line spacing, alignment and hyphenation. Four examples are included: Kobalt, Bookish, Modern and Classic. Create, rename, update or delete presets, and choose one as the default for new books.
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My Words. Save dictionary lookups and revisit their definitions and reading context. Words can be saved automatically or added and removed from the dictionary popup.
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More capable book search. Search the whole book, the current chapter, everything up to the current page or everything after it. Results are no longer limited to an initial batch. The scope heading shows the match total, while the bottom counter shows the current results page and total pages. Tap the counter to jump to another results page.
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Footnotes below the text. Settings > Styling > Book content now offers page-bottom footnotes for books with supported note markup. Long notes continue across pages, and footnote popups remain available. This option is off by default.
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Custom bookmark icons. Add simple SVG icons to
.adds/kobalt/custom-pins/on Kobo, then close and reopen the book. Custom icons appear before the built-in choices. Icons use the current theme's ink colour; complex or unsupported SVGs are skipped, with an explanation in the picker.
Other additions
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Added more sleep-screen designs, including Framed, which keeps progress information below the cover rather than over the artwork.
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Added Hide this book while asleep under Settings > System. This per-book choice hides the cover and identifying text from sleep and power-off screens while retaining anonymous progress information.
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Hide unneeded features under Settings > System to simplify the interface. Saved bookmarks, annotations and words are retained. Hiding KOSync also stops its sync activity.
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Redesigned the synced-position prompt with a graph showing where you are and where the other device would take you. Chapter names, direction and percentages make the choice clearer.
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Added optional document metadata to KOSync uploads, allowing compatible servers to display book titles and authors. It is off by default.
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Added HTTP support for self-hosted KOSync servers, including custom ports and path prefixes. HTTPS remains the default. HTTP does not encrypt authentication or reading progress.
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Added an optional Normalize text colors rule to Book normalization. It uses black text in light mode and white text in dark mode, without changing the original EPUB.
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Added reversed page-turn swipes, an option to keep the Kobalt logo visible while opening books, and pinned bookmark shortcuts beside Stats.
What's fixed
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Fixed books with very large tables of contents failing to open. Kobalt now supports up to 10,000 entries.
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Improved figure and caption layout so suitable figures stay with their captions without moving later paragraphs ahead of them.
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Removed unwanted empty pages before some chapters.
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Fixed saved hardware-button actions following the wrong direction after rotation. Page buttons also work in the sleep-screen and text-preset galleries.
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Corrected chapter-graph proportions and kept bar widths consistent between pages. A zoom button switches between wider bars and more chapters at once. Session statistics now count page turns rather than distinct pages visited.
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Prevented automatic standby while a book is still opening.
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Improved saving native Kobo reading positions in books with duplicate chapter IDs.
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Closing Settings now returns directly to reading.
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Improved small-screen and large-text layouts, light-theme contrast, dialog sizing and refresh behaviour while typing.
Android
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Fixed books failing to open on Android 9 and 10.
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Added Library > More > Resource folders for sideloaded fonts, dictionaries and custom bookmark icons. Choose separate folders on internal storage or an SD card. Fonts support TTF and OTF; dictionaries use Kobalt's supported StarDict format. Close and reopen a book after changing the files.
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Fixed returning to the Library when the system navigation bar was hidden.
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Android remains experimental.
Installation on Kobo
The easiest method is Install or remove on Kobo in Chrome. For manual installation, download the package for your firmware:
- Kobalt-qt5.zip for firmware 4.38.21908 and later 4.x, tested up to 4.46.
- Kobalt-qt6.zip for firmware 5.18 and later 5.x, and 6.x.
Manual installation instructions
- Connect your Kobo over USB and extract the ZIP on your computer. Show hidden files to see
.addsand.kobo. - Copy the package's
assetsfolder into.adds/kobalton the Kobo, replacing matching package files. Preserve your other files and folders. - Copy
KoboRoot.tgzfor Qt5, orKobo.tgzfor Qt6, into the Kobo's.kobofolder. - Eject safely, disconnect USB and let the update install.
Copy the assets before the system package. Leave the .tgz compressed. Do not replace the entire .adds, .adds/kobalt or .kobo folder, as this can remove existing data or other mods.
Upgrading from beta 7
Upgrade over the existing installation; a clean install is not required. Close Kobalt and back up .adds/kobalt before updating. Keep that folder to retain your reading positions, book settings, bookmarks and annotations. The website is the easiest way to upgrade.
Beta 8 upgrades the saved-data database. Older betas cannot read the upgraded database, so keep your pre-upgrade backup if you may want to downgrade.
Books may need to repaginate after updating, and some page counts may change because of the layout fixes.
For installations still on older betas, legacy reading positions, book settings and bookmarks are imported into kobalt.sqlite. Migrated files are retained under migration-backup/. This is a historical backup and does not contain subsequent reading changes.
Installation on Android
Download Kobalt-android-arm64.apk and install it manually. Allow installation from the app opening the APK if Android asks. Android 9 or later on an ARM64 device is required.