Readwise is free for the first 30 days, after which it costs a small monthly fee.
You can currently use Readwise free for the next days. To get more time either:
Your Kindle highlights haven't been able to sync automatically because your Amazon account is logged out.
We now have a native iOS app in beta! You can install it through Testflight by using this link from your iPhone or iPad:
We also have a native Android app coming up on our roadmap!
Alternatively, if you just want to pin the Readwise site to your phone homescreen, we have iOS instructions, and Android instructions here.