SAPI (Speech Application Programming Interface) is a Microsoft Windows API that allows desktop applications to implement speech synthesis. When an application supports SAPI, it can access any of the installed SAPI voices to generate speech. Out of the box, Microsoft Windows provides one SAPI male and female voice that can be used in any supported voice application. With Amazon Polly for Windows, users can install over 50 additional voices across over 25 languages, paying only for what they use. For more details, please visit the Amazon Polly documentation, check the full list of text-to-speech voices, log in to the Amazon Polly console to try them out, and review our pricing, regional availability, service limits, and updated FAQs.