Open source text to speech released under an MIT or Apache license can generally be used commercially, as long as you keep the license and copyright notices. Check the model weights and voices separately, since they can carry stricter terms. If you'd rather not manage code and licenses yourself, Adobe Firefly's text to speech produces audio designed for commercial use.
Maybe you're adding narration to a product demo, building voice into an app, or producing training videos for clients. Free tools are tempting, but "free to download" and "free for commercial use" aren't the same thing. The license attached to the code, the model, and each voice decides what you can sell, ship, or publish. Here's how the most common licenses work and which free options allow commercial use.
Yes, with limits. Major cloud APIs offer free monthly allowances, and some open models are free to run on your own hardware. Cloud APIs are commercial services, so their terms of service govern how you use the audio, not an open source license. Open models, on the other hand, come with a license file that spells out your rights.
Adobe Firefly sits in a third category. It's a creative platform where you generate speech, download the file, and use it in videos, podcasts, and other projects, with audio from the Firefly Speech model designed for commercial use. The table below compares four options.
The Apache 2.0 license is one of the most permissive open source licenses for commercial work. It lets you use, modify, and distribute the software, including inside paid products, without paying royalties or releasing your own source code.
In exchange, you have a few duties. You must include a copy of the license with anything you distribute, keep existing copyright and attribution notices, pass along any NOTICE file the project includes, and mark files you've changed. Apache 2.0 also grants users a patent license from contributors, which gives businesses extra protection that the shorter MIT license doesn't spell out.
Kokoro-82M is a good example. Its creator released the model weights under Apache 2.0 and states the model was trained only on permissively licensed and non-copyrighted audio, which makes it a common pick for commercial projects.
For AI text to speech, the code license and the model license are often different, and the model license usually decides commercial use. A project's code can be open source while its trained weights carry a restrictive license of their own.
Coqui's XTTS-v2 shows why this matters. The model is distributed under the Coqui Public Model License, which allows only non-commercial use of the model and its outputs. That means even audio you generate with it can't be used in revenue-generating work.
Before you build on any open model, check three things: the license on the code, the license on the weights, and the license on each voice or speaker dataset. If all three allow commercial use, you're on solid ground. If any one of them says non-commercial, the strictest term wins.
Often, yes. The MaryTTS core system is released under the GNU Lesser General Public License (LGPL) version 3, as are its language components for English, German, Telugu, and Turkish. The LGPL lets you use the library in commercial and closed-source software, as long as you follow its rules.
The main rules involve changes and replacement. If you modify MaryTTS itself, you must share those changes under the LGPL. If you distribute a product that uses it, users must be able to swap in their own version of the library.
Voices are a separate question. MaryTTS voices are distributed under different licenses, including the Arctic license, a Creative Commons Attribution-NoDerivatives license, and the MBROLA license. Read each voice's license before you ship, since a permissive engine doesn't guarantee a permissive voice.
No. Adobe Firefly is a commercial service, not open source software. You can use its text to speech for free with an Adobe account, which includes free daily generations, and audio from the Firefly Speech model is designed for commercial use.
Both allow commercial use. The MIT license is short and mainly asks you to keep the copyright and license notice. Apache 2.0 adds an explicit patent grant and requires you to mark changed files and keep any NOTICE file.
Not always. Google Cloud Text-to-Speech resets its free allowance each month, while Amazon Polly's free tier applies during your first 12 months. Check each provider's pricing page before you plan a long-term project around free usage.
Supriyo Khan
Supriyo Khan
Supriyo Khan
Supriyo Khan
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