[PeterT]

See this section on Sideloading in a Kobo document on their readers --> https://github.com/kobolabs/epub-spe...sting-purposes

Sideloading for Testing Purposes
Kobo encourages the testing of content on all its reading platforms by sideloading. Content should display identically whether sideloaded or downloaded to a device from the Kobo store. Instances where this is not the case can be reported to renderingissues@kobo.com and the EPUB in question will be logged for investigation.

Here’s how to sideload content on Kobo's reading platforms:

eInk

1. Connect the device to your computer via USB.
2. Find the drive on your computer in Finder or Windows Explorer.
3. Drag your EPUB onto the device. To trigger the Kobo WebKit, change the file extension to .kepub.epub. To trigger the Kobo WebKit for a Fixed Layout title, change the extension to .fxl.kepub.epub. (If the extension is left unchanged it will render using the Adobe Digital Editions WebKit. This is the default display engine for sideloaded content to enable bookmarking, searching and highlighting.)
4. Disconnect your device. The file will automatically appear in your library.

Sideloaded EPUBs with the ".fxl.kepub.epub" or ".kepub.epub" will disable bookmarking and note keeping. Thumbnails for covers may not display. Otherwise the reading experience and content display will be identical to how the file would display when loaded through the store. Leaving the extension as ".epub" will enable bookmarking and note keeping and will trigger the ADE display engine.


Desktop

1. Open the Kobo Desktop app.
2. Make sure you have Adobe Digital Editions installed. If you do not wish to install ADE you can skip this step by creating a folder named "My Digital Editions" in your "My Documents" folder. On a Mac, the folder must be named "Digital Editions" instead.
3. Select the My Books tab in Kobo Desktop and press CTRL+Shift+S on Windows or ⌘+SHIFT+S on a Mac. This will display any files in the "My Digital Editions" folder on your computer with the extension .epub
4. Any sideloaded books can be removed from the My Books tab by right clicking on the book and selecting "Remove Download".

Android

1. Connect the device to your computer via USB.
2. Find the drive on your computer in Windows Explorer. If you use a Mac, install and connect to the device using Android File Transfer.
3. Drag your EPUB onto the device.
4. If you use a Kobo Arc, navigate to the Books Collection. Otherwise, navigate to the Kobo App, then tap the side bar menu icon on the top left (the icon with the three horizontal bars vertically stacked) to bring out the sidebar. Then tap on either 'All' or 'All Items' based on your app version.
5. Select options (the three dots on the top right) then "Import".
6. Once the files appear, confirm that you want to import them. They will display in your library.

iOS

1. Connect the device to your computer with the iOS cable.
2. Open iTunes and click the device's icon in the upper-left corner of iTunes.
3. Select File Sharing from the Settings menu on the left.
4. Select the Kobo Books app from the Apps box in the iTunes window.
5. Drag the EPUB to the Kobo Books Documents box in the iTunes window. If drag and drop functionality is not working then select the "Add File..." button and select the EPUB you want to add to the app. The file will then automatically import and display in your library. If it does not appear even after refreshing your library, closing the app and opening it again should cause the sideloaded titles to appear.

(The Kobo iOS app is registered among apps that open EPUB and pdf files. Users can use the standard "open in…" menu from Safari, Dropbox, or any other app that supports it to view their files.)