To use this app, accept the microphone permissions on page load and then just say something outloud. Once working, enable the transcription.
Please note that this app uses your default microphone as the audio input source.
You sometimes can change the default audio source via the browser's setting, but you can also change it at your system level by changing the default recording device.
You can also change audio sources by using a Virtual Audio Cable, such as this one.
Using it, it becomes possible to select other sources, including microphones, speakers, and other applications.
The translation is powered by Google Cloud Translation, which requires an API key for extended use (add &key=xxxxxxx to the URL to specify it). For trial use, I'm providing access with my own key by default, but I may limit usage to avoid abuse.