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General info on eBooks

What is an EPUB?

An EPUB is an open standard file format for publishing electronic books which can be transferred to a device for reading. There are two main types of EPUB to choose from, a ‘flowing’ EPUB and a ‘fixed format’ EPUB. The flowing EPUB has been designed for text heavy books, such as novels. Fonts and type sizes can be changed by the reader and text will reflow to fit the space allowed. It is therefore largely unsuitable for illustrated books and complex page structures. The EPUB format is published and maintained by IDPF and the latest version is EPUB3 supported by Adobe, Apple, Kobo, Google and many other software companies and major publishers. EPUB is supported by the majority of eBook stores and eReading devices. The notable exception is Amazon who has its own formats (see What is a fixed layout KF8?)

What is a fixed layout EPUB?

A Fixed Layout EPUB (or ‘FLO’ EPUB) is, as the name suggests, a way for graphically designed books to be displayed and read as the designer intended. The fixed layout EPUB format maintains the positioning of design, layout, images and text. This means that professionally designed book pages can be preserved. The reader can zoom in to a passage of text but the words will not reflow. Apple sells both standard EPUB and Fixed Layout EPUB in the iBookstore, as do Kobo, Google Play and more.

Fixed layout EPUBs can contain links, movies, audio, animation, read-aloud and more.

What is a fixed layout KF8?

A Fixed Layout KF8 is Amazon’s own type of ebook file format which, like the fixed layout EPUB, maintains the positioning of design and layout and supports live text searching, highlighting and bookmarks. Most KF8 devices including Kindle Fire support pinch and zoom or alternatively offer s different way to enlarge text called ‘mag zones’ where readers tap on a paragraph of text to open the live selectable text in a larger panel above the page.

Fixed layout KF8 can not contain movies, audio or animation.

How can I read fixed layout eBooks?

There are an increasing number of ways to open and read fixed layout EPUB3 and KF8 on tablets, Mac/PC and mobile devices.

Apple offer iBooks freely for the iPad, iPhone and iPod Touch and Mac 10.9 and later.

Adobe Digital Editions is available for iOS and Android devices and desktop Mac and PC.

The Kobo Arc device supports fixed layout EPUB3 and Kobo make reading Apps for a range of devices including Android tablets.

The IDPF makes Readium – an open source EPUB3 which brings fixed layout reading to Mac, PC and mobile via the browser.

Google Books makes is possible to upload fixed layout EPUB3 to Google Books and then read using their Google Books app for Android devices or iOS.

Amazon KF8 format is best supported by their Kindle Fire although also available on other Kindle devices, Kindle for iPad and Kindle desktop readers. Good instructions on how to add a .mobi file to a Kindle Fire device are here.

General info on CircularFLO

What is CircularFLO?

CircularFLO is a Mac only application which writes all the code required to create a fixed layout EPUB3 and KF8 from an Adobe InDesign book without coding. It uses Adobe InDesign CS6 to generate content than recreates all the pages and supporting code, packages into an EPUB3 and validates.

Do I have to use a Mac to work with CircularFLO?

Yes. The Mac OS X is heavily used by CircularFLO throughout the process to create and package the eBook. CircularFLO runs on the Mac only and we have no plans to make a Windows version in the near future. See System Requirements here.

Do I have to use InDesign to work with CircularFLO?

Yes. CircularFLO creates fixed layout EPUBs that are exact replicas of professionally designed and illustrated pages. It has been built to work with graphic designers and publishers’ favourite layout program, Adobe InDesign. See System Requirements here

What design restrictions do I have to work within for CircularFLO?

There are no design restrictions with CircularFLO on regular layers. Anything and everything that has been created for a print publication in Adobe InDesign can replicated in eBooks from CircularFLO.

There are however some considerations when using live text see out Adding live text instructions

Are my words embedded in my EPUB?

Yes. CircularFLO creates fixed layout eBooks that contain either embedded or live text. All words that are set in InDesign along with their position on the page are reproduced. This means the text is accessible by reading systems for the visually impaired and the entire eBook can be searched easily in most eBook readers.

Are my fonts embedded in my EPUB?

Yes and No. For embedded text, CircularFLO creates fixed layout eBooks that are exact replicas of professionally designed and illustrated pages but without embedding the fonts. This means any and all fonts can be used without worries of licensing problems or file format restrictions. For live text, words are displayed using the font and these fonts are embedded.

What is 'live text' and 'embedded text'?

CircularFLO supports three kinds of text embedding and each one has advantages and disadvantages. Let’s go through each one in turn;

1. Live Text

These words are able to be highlighted by tapping and holding on a word or phrase. Highlighted live text can be copied or used in searches. CircularFLO will look for InDesign styled text within frames placed on a layer named FLO_LIVE_TEXT and these will be reproduced in your eBook as live text.

Pros of live text

  • Text can be selected to be looked up in the in built dictionary or online.
  • Text is very crisp even when zoomed to maximum magnification.
  • When searching the eBook, found text is then highlighted on the page.
  • Double tapping zooms in and out of the live text area.

Cons of live text

  • PostScript fonts are not supported in eBook and must be substituted.
  • The differences between InDesign’s more sophisticated text engine and typography controls and those available in HTML / CSS formatting can sometimes make text conversions position and reflow slightly.
  • Graphic styling e.g. Strokes, gradients, shadows and blend modes are not supported.
  • Text must be styled in InDesign and the styles uses must be present in the ‘style source’ of the book.
  • Text must appear on top of images.
  • Fonts are embedded in the eBook.

2. Embedded Text

With embedded text, all words set in InDesign appear in the eBook as an exact replica. The words are embedded but the fonts are not, making the words fully searchable without the design constrictions of live text. 

Pros of embedded text

  • Text is displayed exactly as set and designed in InDesign.
  • Fonts used on embedded text are not embedded, so there are no restrictions on the format or problems with licensing.
  • Text remains fully searchable.
  • No need to apply styles to text in InDesign.
  • Text can be placed behind images.

 Cons of embedded text

  • When searching the eBook text the result page is displayed but words are not highlighted.
  • Text is a converted to high resolution images but at maximum zoom the text may seem a little softer than live text.

3. Image Text

Image text is not really text at all. Any text set outside of InDesign e.g. in Illustrator or Photoshop is treated as an image and converted to high a resolution image in the eBook.

Pros of image text

  • Any graphical effects can be used e.g. Warps, perspectives and more heavy styling can be used.

Cons of image text

  • There are no words embedded and therefore no searching or highlighting available.


Are Korean, Chinese, Japanese and other 'double byte' languages available?

Yes. We take our HTML outputs directly from InDesign, so CircularFLO supports all the character sets that OpenType and InDesign supports including Korean, Chinese and Japanese and can convert to live text in your EPUB3 and KF8.

Can CircularFLO convert PDFs to eBooks?

Yes, in so much as that it works with InDesign and InDesign can accept PDF as a image format. Exact replicas of PDFs will be produced, however any text in PDFs will not be embedded. Only text that is set in InDesign will be embedded and be searchable in the eBook.

Can CircularFLO convert Microsoft Word documents?

No, although InDesign can accept Microsoft Word as a text format it will not maintain the layout exactly. The flowing EPUB format is more suited to Microsoft Word text documents and there are many conversion services available to help you do this.

Free trial mode and proofing

How can I preview my EPUB before paying for it?

CircularFLO runs in trial mode free of charge so you can produce a 10 page sampler eBook to see how your eBook pages will appear see How can I read fixed layout eBooks? 
With at least one purchased eBook credit loaded, you can create as many full page length proof versions before committing to using your credit.

What is 'trial mode' and what is 'proof mode'?

CircularFLO runs in trial mode free of charge. In trial mode only the cover and the first 10 pages are produced and a watermark is applied to the pages which contains a link to our website. To produce an entire book as an eBook an eBook Credit must be purchased.
Once a credit is loaded, and whilst it remains unused, any number of eBooks of the entire page range can be produced in ‘proof mode’. In proof mode a watermark is applied which contains a link to our website.

What is the difference between an eBook made in trial or proof mode and a purchased EPUB?

When an eBook credit is used and CircularFLO is run in ‘live mode’ all pages have their watermarks removed and a validated EPUB3 and KF8 compatible file is created that is ready for distribution and sale. To produce an entire book as an EPUB without watermarks an eBook Credit must be purchased.

What is an eBook Credit?

An eBook Credit unlocks CircularFLO to produce an entire InDesign book as an fixed layout EPUB without watermarks. Each eBook requires one Book Credit regardless of page extent.

Can I update my eBooks without charge?

Yes. Once an eBook credit has been used on an InDesign book, that InDesign book and documents can then be updated and re-made as many times as required without any further charge. To prevent misuse, you are restricted to using the same documents and can’t swap or introduce new documents into the book.

On remaking, a version number can be entered in the EPUB3 and Apple use the internal version number as a way of issuing update notification to your readers using iBooks.

Purchasing your Book Credits

How much does it cost?

CircularFLO runs in trial mode free of charge. ‘eBook Credits’ are purchased in advance and an emailed code then unlocks CircularFLO to create your purchased eBooks. One credit is required for each eBook produced.

We have two prices, a ‘CircularFLO Instant’ book credit is available for books of up to fifty pages and can be both a KF8 and fixed layout EPUB3 in a single file containing live or embedded text, hyperlinks and table of content information.

A ‘CircularFLO Pro’ book credit can contain live or embedded text, hyperlinks and table of contents info but there is no restriction on the number of pages in a book and each fixed layout EPUB can also include audio, video, animation and read aloud text highlighting.

Current pricing is available on our pricing page.

How do I purchase my Book Credit?

To purchase a Book Credit, select your currency on our pricing page, enter your unique ID number to pay then pay quickly and securely with PayPal.

Once payment is processed (which is immediate with PayPal) an email containing your eBook credits is sent back to the purchaser’s email within minutes ready for loading into CircularFLO.

Invoicing and bulk purchase discounts are available for larger customers starting with orders of over ten Pro Credits. Please contact us for more details.

Why do I have to pay for my eBook Credit in advance?

The eBooks produced by CircularFLO are ready to immediately share, view and upload to the bookstores. CircularFLO is commercial software and therefore we must ask for your payment up front as there is no way for us to charge afterwards.

Can I use CircularFLO on more than one Mac?

Yes, CircularFLO is free to install on as many Macs as you want. However purchased eBook Credits are only valid for the unique ID that was entered when purchasing and eBook Credits are not transferrable between Macs.

Do purchased eBook Credits run out?

Book Credits must be loaded into CircularFLO within one month. Once loaded there is no time limit for them to be used.

Can I run CircularFLO in trial or proof mode when I have purchased credits?

Yes, there is an option to CircularFLO run in the free trial mode at any time, and when eBook Credits have been loaded full page length proof eBooks can be generated.

Viewing and publishing your purchased EPUB

How can I view my eBook created by CircularFLO?

The eBook produced by CircularFLO is immediately ready to sync to iBooks on your Apple device via iTunes or transfer to your Kindle Fire via USB (Drop the KF8 .mobi file into the documents folder).

You can also open the EPUB in Readium directly on your Mac’s Chrome browser.

See also How can I read fixed layout eBooks?

Does CircularFLO produce eBooks only for the iPad?

No. By supporting the latest EPUB3 standard your eBooks can be viewed on a wide range of devices, Mac and PC.

See also How can I read fixed layout eBooks?

Do eBooks from CircularFLO support audio and video?

Yes. It’s simple to add enhancements to the flat page by adding video and audio files. Audio can be played with a tap and video can be run in position or the reader can zoom to full screen, returning to the page when complete. See the instructions page for full info.

The KF8 format does not support audio or video at the time of writing.

How can I upload my eBook to the iBookstore and Kindle Store?

We have partnered with BookBaby to make it easy for you to get the eBooks made with CircularFLO on sale in the Apple iBook Store.

The EPUBs produced from CircularFLO are valid and passing the latest version of EpubCheck. Once uploaded, Apple will then review the content before allowing onto the iBookstore.

For those wanting to go it alone, Apple provide an automatic process and extra software ‘iTunes Connect’ for publishers to upload to files to the iBookstore. For more details visit their iTunes Connect pages here.

Amazon Kindle Direct Publishing (KDP) is a way for self publishers to quickly upload books for sale in the Kindle Store. Rather than sending the preview .mobi file which CircularFLO can generate we recommend uploading the smaller .epub file to KDP which still contains all the KF8 code and will be converted by Amazon.

Need instructions on preparing documents and running CircularFLO? Check out our Instructions page.

Mac, Mac OS, iPad, iPhone, iPod, iPod Touch, iTunes, iTunes Connect, iBooks, iBooks Author, iBookstore are registered trademarks of Apple Inc. • Adobe, Adobe Creative Suite, Adobe InDesign, Adobe Photoshop and Adobe Illustrator are either registered trademarks or trademarks of Adobe Systems Incorporated in the United States and/or other countries. • Amazon, Amazon Kindle, Kindle Fire, Kindle Previewer and Kindlegen are re either registered trademarks or trademarks of, Inc. in the United States and/or other countries.