The AVS Sample App is great to play with on a Raspberry Pi as a cheaper, more home-made version of Alexa. However, both the wake word engines (TrulyHandsfree and Kitt.AI) have problematic licenses.

By free, I'm looking for an engine where both the code and the training data provided is licensed for use for both personal and commercial uses. The TrulyHandsfree engine has a very restrictive license permitting personal use only, and the binaries they provide stop working entirely after about 3 months to try and discourage unlicensed use. The Kitt.AI engine is slightly better, but their webpage specifically says that the "Hacker" pricing (their free tier) does not have a commercial license.

Does Amazon provide a more free wake word engine, or are there any engines that support the AVS sample with less restrictive licensing?

  • 1
    You could look into the Mycroft project to see what they do. Commented Dec 19, 2017 at 7:10

2 Answers 2


HomeAssistant now includes an entirely open source voice assistant toolchain.

  • OpenWakeWord is the open source wakeword engine; it's licensed under the Apache 2.0 license.
  • faster-whisper is the open source speech-to-text engine; it's licensed under the MIT license.
  • Piper is the open source text-to-speech engine; it's also MIT licensed.

You should be able to use any or all of these projects. HA supports a myriad of languages, but I'm not sure where the training data is.


Have you tried Porcupine? It's a pretty well maintained open source project and has an Apache 2.0 license.

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