Does Readwise automatically sync my Kindle highlights?

Yes! At least, most of the time.

If you (1) use the Chrome or Firefox browser on your computer and (2) keep the Readwise browser extension installed, then Readwise will automatically sync your Kindle highlights. 

Caveats

• Occasionally, your browser will be logged out of the Kindle notebook page. If this happens, Readwise will display an orange dot on your Dashboard prompting you to log back in.
• If you read personal documents on your Kindle device or in a Kindle app, those highlights will not be automatically synced with Readwise. Amazon does not synchronize highlights of personal documents to the cloud the same way it does highlights of books purchased or borrowed through the Kindle store. You can use one of the methods described here: How do I import highlights from documents I sent to my Kindle?

If Readwise notices you have not synchronized new Kindle highlights in the past 45 days, you'll receive an email reminding you to resync.