You can use text-to-speech in the Kindle app on an iPad using an accessibility feature — here's how to turn it on

The Kindle iPad app doesn't have text-to-speech built in, but you can use the iPad's own Speak Screen feature as a replacement.
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Google Read Aloud User Agent Updates Which Services Use It

Google has updated the list of Google products and services that use the Google Read Aloud user agent. The updated page also says that the "service provides an audio version of web pages by ...