I need help to convert audio to text / text to audio in the website backend

in my project I have a microcontroller that sends some voice data (which is via a microphone) to a website (the entire voice data gets sent through HTTP body and NOT streaming).

I need the website (backend) to do the following tasks:

problem 1: converting the recived voice to text

problem 2: also converting a text to audio (.mp3)

I need some guide on how each one of the above tasks can get done in general. I mean what lanuage/library or framework can be used as a solution? HTML? javascript? any php or other languages libraries? any website with free API?

I appreciate your help on the two problems. Thanks in advance.

Through googleing I just found out that HTML5 SpeechSynthesis API can do text to audio (problem 2), But how to get the audio as .mp3?

source https://stackoverflow.com/questions/76296587/i-need-help-to-convert-audio-to-text-text-to-audio-in-the-website-backend