A free program for Android, by Voice Text.

Voice Typing Tool — Speech to Text Converter Tools is an Android app that provides different speech-to-text conversion tools. Download it for free and use it to convert your audio files into text. It provides a lot of options for you to choose from. You can use it for dictation or for messages sent via email or SMS. It also has the option to make it speak the results.

How to use it?

This app can be used in two ways. You can choose to do a conversion using the audio or the text file.

You can also use the browser to search for what you want to convert into text.