Google sells access to their TTS service at https://cloud.google.com/text-to-speech/. They advertise that you can use it for free, if you use less than 4 million letters (1 million for WaveNet voices).

I couldn't find any information regarding the license terms of the generated audio files. So, what may I do with the generated sound files? I mean often you need the same sounds again and again. May I cache the sound files? May I play them to the public? Redistribute them with my app? Offer them as a download? Sell them?

To use the TTS service you have to accept the Google Cloud Platform Terms of Service (https://console.cloud.google.com/tos?id=cloud). I think the most relevant part is the following section:

5.1 Intellectual Property Rights. Except as expressly set forth in this Agreement, this Agreement does not grant either party any rights, implied or otherwise, to the other’s content or any of the other’s intellectual property. As between the parties, Customer owns all Intellectual Property Rights in Customer Data and the Application or Project (if applicable), and Google owns all Intellectual Property Rights in the Services and Software.


Just at the offset this does not constitute legal advice, just some opinions I have on this point. Technically, you would not be prohibited to generate speech and use it however you like. Under normal circumstances any output generated by the system that does not contravene the service agreement would be your intellectual property. This would include the text and speech generated. Once you go about the request limit you would naturally be required to pay, but until that time you can use the service as a paying customer.

Just to clarify this point I would like to make reference to the service license agreement, clause 3, which make reference to the following prohibitions:

(a) copy, modify, create a derivative work of, reverse engineer, decompile, translate, disassemble, or otherwise attempt to extract any or all of the source code of the Services (subject to Section 3.4 below and except to the extent such restriction is expressly prohibited by applicable law); (b) use the Services for High Risk Activities; (c) sublicense, resell, or distribute any or all of the Services separate from any integrated Application; (d) create multiple Applications, Accounts, or Projects to simulate or act as a single Application, Account, or Project (respectively) or otherwise access the Services in a manner intended to avoid incurring Fees or exceed usage limits or quotas; (e) unless otherwise set forth in the Service Specific Terms, use the Services to operate or enable any telecommunications service or in connection with any Application that allows Customer End Users to place calls or to receive calls from any public switched telephone network; or (f) process or store any Customer Data that is subject to the International Traffic in Arms Regulations maintained by the Department of State. Unless otherwise specified in writing by Google, Google does not intend uses of the Services to create obligations under HIPAA, and makes no representations that the Services satisfy HIPAA requirements. If Customer is (or becomes) a Covered Entity or Business Associate, as defined in HIPAA, Customer will not use the Services for any purpose or in any manner involving Protected Health Information (as defined in HIPAA) unless Customer has received prior written consent to such use from Google.

Similarly, as specified here:

Customer will not, and will not allow third parties to: (i) use these Services to create, train, or improve (directly or indirectly) a similar or competing product or service or (ii) integrate these Services with any applications for any embedded devices such as cars, TVs, appliances, or speakers​ without Google's prior written permission. These Services can only be integrated with applications for the following personal computing devices: smartphones, tablets, laptops, and desktops. In addition to any other available remedies, Google may immediately suspend or terminate Customer's use of these Services based on any suspected violation of these terms, and violation of these terms is deemed violation of Google's Intellectual Property Rights. Customer will provide Google with any assistance Google requests to reasonably confirm compliance with these terms (including interviews with Customer employees and inspection of Customer source code, model training data, and engineering documentation). These terms will survive termination or expiration of the Agreement.

You should also take a look at this and this.

However, as per the terms of the agreement the speech generated would be your intellectual property, unless otherwise specified.

Good luck!

  • 1
    Thanks for your research! I decided to use amazon polly instead. They provide a very clear FAQ (aws.amazon.com/polly/faqs).
    – someonr
    Mar 20 '19 at 10:45
  • Good to know! I absolutely agree, AWS has been in the game for far longer and has done a really good job in providing relevant information to users. Mar 20 '19 at 12:10

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