Amazon launches a Polly WordPress plugin that turns blog posts into audio, including podcasts - AWS in the News
Amazon Polly for WordPress — WordPress Plugins
Amazon launches a Polly WordPress plugin that turns blog posts into audio, including podcasts | TechCrunch
Amazon Polly Pricing
"The Amazon Polly free tier includes 5 million characters per month for speech or Speech Marks requests, for the first 12 months, starting from your first request for speech.
$4.00 per 1 million characters for speech (~23 hours, 8 min)
Microsoft Azure "Cognitive Service" / Bing has a similar service / API, at least it used to have it.
Speech-to-text is still there. Current list of service does not include text-to-speech.
Similar API is available in Windows, but with smaller number of "Agent" voices.
Cognitive Service Try experience | Microsoft Azure
GCP also includes only speech-to-text, , no text-to-speech, only provides "reader" Android app.
Cloud Natural Language | Google Cloud Platform
Related, Amazon also started offering translation service with limited set of languages, but extensible
Amazon Translate – Neural Machine Translation - AWS
A quick look at Machine Translation with Amazon Translate