If you use the large-v2 model they expose via the API, the more accurate, in your local machine, you'll see that even though it works great it's slow and won't work for long audio files because of memory limitations.

It's fairly easy and quick to run Whisper for free either locally in an Anaconda environment with Python or the command-line interface or, even better, in a Google Colab notebook.

Here's a sample notebook that builds on a notebook by Pete Warden.

https://colab.research.google.com/drive/1sxsey3n0jd09MjUd9Ky...