Calibre 8.9 now supports HTMLZ export and improves support for KEPUB and Kobo.

  • Calibre 8.9 refines edition (NFC), HTMLZ with sources, recent news and merge with destination cover.
  • The 8.x series jump is maintained: local Piper TTS, native KEPUB and much faster viewer.
  • Conversion and format tips: Avoid PDF as a source, check encoding, and use correct indexes in MOBI.
  • Devices and server: Kobo built-in, Kindle with cover tricks, Android/iOS via OPDS, and more stable server.
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7 minutes

Caliber 8.9

Caliber 8.9 comes with a batch of useful improvements that fine-tune the daily experience: from output compatibility like HTMLZ with embedded fonts to interface, server, and editing tweaks that save you clicks. If you're coming from the v8.0 or earlier, you'll notice that many of the big new features are still around, such as the Piper neural voice engine and native KEPUB support for Kobo.

This review brings together the highlights of version 8.9 and also a look back at the great features introduced in the 8.x series that continue to make a difference. Plus, we've integrated conversion tips, format compatibility, device tricks (Kobo, Kindle, Android, iOS), and common troubleshooting tips into a single, handy resource.

Main new features of Caliber 8.9

Update 8.9 focuses on refinements You'll notice these improvements right away when managing your library and editing books. These are the most noticeable improvements:

  • HTMLZ now supports embedded fonts, so your exports will effortlessly retain custom fonts.
  • Annotation Browser: A color swatch is added to the results to identify the type of highlighting on the fly.
  • Joining books by drag and drop: When merging titles you can see the cover of destiny, avoiding surprises when consolidating records.
  • get news: New right-click submenu with recently downloaded fonts to relaunch them in a second.
  • Plugin Installation: Filter by category to find the plugin you're looking for faster.
  • Best Book Pairing When initially searching by device title: If there are no matches, text in parentheses or after a colon is ignored to improve the match.
  • Content server: Fixed a bug when editing metadata by changing cover and other field at once.
  • TTS voice selection: Improved selection box to choose the most comfortable reading voice.
  • Book publishing: Text pasted from the clipboard is normalized to NFC form, avoiding oddities with accents and compound characters.
  • News sources: The New York Times, Todoist and Tagespost have been updated, and Startechery has been added as a new source. More variety of content daily.

Calibre 8.9 introduces noticeable interface and productivity improvements

Small details, big impactViewing the target cover when merging, quickly relaunching your favorite news sources, or filtering plugins by category speeds up everyday workflows. If you manage a large library, improved title matching on the device prevents duplicates and confusion.

Normalization to NFC when pasting text It means fewer invisible issues with tildes and special characters, especially useful if you're editing metadata or touching HTML/CSS within the built-in editor.

Editing and formats: what wins 8.9 and what was already mature

With 8.9, HTMLZ improves with embedded fonts, a common request for preserving fonts in lightweight packages. Combined with NFC standardization upon pasting, the edition gains reliability and typographic consistency.

If you work with Kobo, KEPUB integration saves time both when editing and sending. And if you're coming from PDF, the 8.x engine that cleans up headers and footers reduces manual retouching, although PDF remains an ungrateful origin for conversion and it is advisable to adjust expectations.

Get news: faster and more yours

Relaunch what you read often It's easier with the recent feeds submenu when you right-click on Get News. In addition to new and updated feeds, you can create your own. formulas For simple sites with full RSS: add title, URL and article limit and Calibre composes a ready-to-read eBook.

When the feed does not bring the full articleCalibre can follow the link and generate the book anyway. And if you're using reading apps, many understand OPDS, so you can browse and download from the Calibre content server on your mobile or tablet wirelessly.

Format compatibility and conversion best practices

  • Admitted entries: AZW, AZW3, AZW4, CBZ, CBR, CB7, CBC, CHM, DJVU, DOCX, EPUB, FB2, FBZ, HTML, HTMLZ, KEPUB, LIT, LRF, MOBI, ODT, PDF, PRC, PDB, PML, RB, RTF, SNB, TCR, TXT, TXTZ.
  • Supported outputs: AZW3, EPUB, DOCX, FB2, HTMLZ, KEPUB, OEB, LIT, LRF, MOBI, PDB, PMLZ, RB, PDF, RTF, SNB, TCR, TXT, TXTZ, ZIP.
  • Best origins by quality (from highest to lowest): LIT, MOBI, AZW, EPUB, KEPUB, AZW3, FB2/FBZ, DOCX, HTML/PRC/ODT/RTF/PDB/TXT and, at the end, PDF. Avoid PDF if you can; if not, check the chapter on automatic cleanup (8.x) and assume there will be a touch-up.
  • “Exotic” characters (accents, non-Latin, smart quotes): Correctly specify the input encoding during conversion. For added HTML, customize the HTML to ZIP plugin with the actual encoding (cp1252 is common on older websites). If you adjust the plugin, leave the encoding empty in the conversion because the plugin already standardizes to UTF-8.
  • Indexes in MOBI: the format doesn't have a real metadata index, it simulates one by inserting an extra index into the book. Calibre generates it at the end by default (you can move it or disable it, but Disabling it may cause problems on your Kindle.). If you have a manual index on the source, use index discovery to map it to the metadata index.
  • Multiple HTML pages in order: Create an index page with links in the desired order and convert it; then adjust the Index options during conversion to control how the table of contents is generated.
  • Valid EPUBs: Calibre prioritizes real device compatibility over strict validity. If you need EPUB 100% valid, feed validated XHTML 1.1 + CSS 2.1; thus the resulting EPUB will be valid.
  • Conversion helpHover over the options in the GUI or use ebook-convert -h in the terminal; there's a demo file with advanced features (html-demo.zip) for practicing.

Devices: Kobo, Kindle, Android, iOS and more

Calibre connects to most readers, mobile phones and tablets directly. And if not, the Connect to Folder feature bridges any device you mount as a USB. You can also use the content server for wireless access via browser.

If your device is weird, the “User defined” plugin allows you to treat it as a standard USB drive (on Windows, it needs a drive letter). Disable the integrated driver if you are going to use the one defined by the user for that same model.

iPad / iPhoneApple no longer allows USB tethering for third-party apps. Use the content server and Safari, or use apps like Marvin/MapleRead/iBooks that support OPDS. Set the primary output to EPUB and the profile on your iPad/iPhone for fine-tuning.

Android: via USB (make sure no other program “grabs” it on macOS/Linux) or via network with the content server. recommended output: EPUB on generic Android, MOBI/AZW3 on Kindle.

Kindle via browserSome models don't access port 8080; change the server to port 80 or redirect it on your router. If you have a basic browser, use the /mobile interface without JavaScript.

Mail and Kindle Features

Send by email Works best in Calibre 8.9 using a stable repeater. Create a free GMX account, enable SMTP, and set Share via Email in Calibre to “Use GMX.” Send to Kindle: Authorize the address on your Amazon account.

Disappearing Kindle e-ink covers: This is an Amazon bug. Trick from Calibre 4.17: Reconnect the Kindle and Calibre will restore the thumbnails. Keep airplane mode prevents Amazon from trying to download your “official” thumbnail.

Kindle ColorSoft and laterAmazon has disabled covers in the list for “non-Amazon” books. Solution: Mark the books as “Personal Documents” (under MOBI Output, turn on Content Sharing). Pros: visible cover. Cons: go to the Documents section and there is no Whispersync.

MOBI covers in Kindle apps (PC/Android/iPad): Check “Enable sharing of workbook content” in the MOBI output to display thumbnails, at the cost of classifying them as Personal Documents.

Books not listed on KindleThe indexer sometimes crashes. Restart your Kindle or upload books one by one until you find the problematic one; convert it back to AZW3 or MOBI and resubmit it.

Amazon and MOBI by email: have announced that they are no longer accepting MOBI via @kindle.com. Send EPUB when possible; if Amazon rejects it, convert EPUB->MOBI and back again from MOBI->EPUB to simplify the file and increase acceptance (you lose advanced formatting and embedded fonts).

Conclusion of the Caliber 8.9 launch

Caliber 8.9 polishes the already solid experienceSpecific improvements to HTMLZ, annotations, book linking, news, and TTS, plus a more stable content server. Added to the major leap forward in 8.0 (Piper neural voice, native KEPUB, a more agile viewer, and cleaner PDF conversion), you have a more well-rounded tool for managing, converting, reading, and sharing your library, with practical tips for overcoming typical Kindle, PDF, and platform-specific issues.