Calibre is brilliant, but many of its features fly under the radar. Here are the best Calibre features to help you manage your ebook collection.

This Calibre plugin allows you to manage your Kindle collections, and, on select devices, margins and fonts.

Main Features
Works on the Kindle DX, 2, 3, and 4 non-touch; and in tandem with ixtab's Collections Manager on JailBroken Kindle Touch, PaperWhite, PaperWhite 2, Basic, Voyage, PaperWhite 3, Oasis, Basic 2, Oasis 2, PaperWhite 4 & Basic 3 devices

Collections Manager offers a much more flexible way than the built-in one to manage Kindle Touch and Kindle PaperWhite collections.

Stop organizing your ebooks like they’re just a tired pile of documents and start organizing them in style with Calibre—an open source ebook organizer that supports metadata, cover flow, format conversion, and more.

Whenever I open an .epub file in Calibre e-book viewer, the text is full-justified. I want to set left-justification as a permanent preference for all .epub files. How can I do that?

I'm running the latest version of Windows 10 Home Edition 64-bit, and the latest version of Calibre (I think), 5.14.

Thanks for any help.

UPDATE: I submitted my question to the MobileRead forum's thread, Custom CSS Stylesheets for Calibre's Viewer, and received an answer from Kovid Goyal, himself (the creator of Calibre). The solution is to use a style sheet (as suggested by Christian__N, below) with this entry:

* { text-align: left !important; }

https://www.mobileread.com/forums/showthread.php?t=51500

In the Ebook Viewer application, click on the Hammer [gear] icon (Preferences), then put the code in the "User stylesheet" edit box and click OK. Have an ebook open in the viewer for the full effect, before and after.