Even web applications, with help of JavaScript APIs exposed by browsers and server-side APIs
can both synthesize and recognize voice.
Getting Started with the Speech Synthesis API - Treehouse Blog (works in Chrome)
Microsoft Cognitive Services
Microsoft Cognitive Services - Bing Speech API
5,000 transactions per month Free
Speech to text Utterance up to 15 seconds $4 per 1000 transactions
Text to speech $4 per 1000 transactions
c# - Calling SpeechAPI for text to speech on Azure - Stack Overflow
Microsoft Cognitive Services - Computer Vision API (image OCR)
Windows speech APIs:
Speech | Context | Channel 9
Microsoft Speech API (SAPI) 5.3
Windows-universal-samples/Samples/SpeechRecognitionAndSynthesis at master · Microsoft/Windows-universal-samples @ GitHub
Speech Recognition and Speech Synthesis in Universal Windows Apps