Free ebooks for adults (Kindle, Nook, Kobo, etc) abound, but the number for kids is much smaller and a bit harder to find IMHO. It occurred to me to share a few I have found lately. My older two (ages 11 and 8) read on Kindle, and the youngers read theirs on ipad as our Kindles are not color/fine graphics (i.e., Kindle Fire) but rather just for reading.
For younger ones, we picked up these freebies lately:
Those were obviously for Eden and Lily (ages 6 and 3). For Zach, I found this freebie today:
He has read one in this series before from the library and really enjoyed it.
Obviously, my links may not be free when you read this, but they are as of this posting so hope you get a chance to grab them if you want them, and keep an eye out as books for kids do go free occasionally, or at least discounted.