GPL in the way!? License issues regarding current source code?


since I am currently scanning the Mozilla TTS source code I came across some possible issues with incompatible licenses. I used the “pip-licenses” package to check all licenses with the current Mozilla TTS github repo (please note, there might be also some irrelevant packages listed since this listing is just from a fresh venv and contains also basic packages, therefore):

 Name                    Version       License                                             
 Flask                   1.1.2         BSD-3-Clause                                        
 Jinja2                  2.11.2        BSD-3-Clause                                        
 Markdown                3.2.1         BSD License                                         
 MarkupSafe              1.1.1         BSD-3-Clause                                        
 SoundFile               0.10.3.post1  BSD 3-Clause License                                
 Unidecode               1.1.1         GPL                                                 
 Werkzeug                1.0.1         BSD-3-Clause                                        
 absl-py                 0.9.0         Apache 2.0                                          
 attrs                   19.3.0        MIT                                                 
 audioread               2.1.8         MIT                                                 
 bokeh                   1.4.0         BSD-3-Clause                                        
 cachetools              4.1.0         MIT                                                 
 cffi                    1.14.0        MIT                                                 
 click                   7.1.1         BSD-3-Clause                                        
 clldutils               3.5.0         Apache 2.0                                          
 colorlog                4.1.0         MIT License                                         
 csvw                    1.7.0         Apache 2.0                                          
 decorator               4.4.2         new BSD License                                     
 future                  0.18.2        MIT                                                 
 google-auth             1.14.1        Apache 2.0                                          
 google-auth-oauthlib    0.4.1         Apache 2.0                                          
 grpcio                  1.28.1        Apache License 2.0                                  
 isodate                 0.6.0         BSD                                                 
 itsdangerous            1.1.0         BSD                                                 
 joblib                  0.14.1        BSD                                                 
 librosa                 0.7.2         ISC                                                 
 llvmlite                0.32.0        BSD                                                 
 numba                   0.49.0        BSD                                                 
 oauthlib                3.1.0         BSD                                                 
 packaging               20.3          BSD or Apache License, Version 2.0                  
 phonemizer              2.2           GPL3                                                
 protobuf                3.11.3        3-Clause BSD License                                
 pyasn1                  0.4.8         BSD                                                 
 pyasn1-modules          0.2.8         BSD-2-Clause                                        
 pycparser               2.20          BSD                                                 
 regex                   2020.4.4      Python Software Foundation License                  
 requests-oauthlib       1.3.0         ISC                                                 
 resampy                 0.2.2         ISC                                                 
 rfc3986                 1.4.0         Apache 2.0                                          
 rsa                     4.0           ASL 2                                               
 scikit-learn            0.22.2.post1  new BSD                                             
 scipy                   1.4.1         BSD                                                 
 segments                2.1.3         Apache 2.0                                          
 tabulate                0.8.7         MIT                                                 
 tensorboard             2.2.1         Apache 2.0                                          
 tensorboard-plugin-wit  1.6.0.post3   Apache 2.0                                          
 tensorboardX            2.0           MIT license                                         
 torch                   1.5.0         BSD-3                                               
 tornado                 6.0.4          
 uritemplate             3.0.1         BSD 3-Clause License or Apache License, Version 2.0
  • As it seems to me, there are two packages which are licensed under GPL,
    Unidecode and phonemizer
  • Afaik, Mozilla’s license allows commercial usage WITHOUT licensing the full code under e.g. Mozilla’s license, as well!? That said, isn’t it incompatible then to use GPL-licensed libraries with the TTS source code and the Mozilla license?

I don’t want to be a spoilsport - but GPL is rather inconvenient for projects also having commercial products in mind.

Can anyone check on this or reply from Mozilla’s legal department maybe? Thanks a lot!

Or to be more precise (i.e. what I really mean): Blending GPL licensed libraries/source code into the Mozilla TTS source code makes it - afaik - inconvenient if not impossible to use Mozilla TTS in commercial closed-source, proprietary (you name it…) projects.

I would like to know if this is by accident or on purpose so that TTS never can be part of commercial solutions without “legal headache”…

Thanks for any clarification - and no offense, please!

You can definitely commercialize a product that use both GPL’ed and closed-source software. The best example of that are routers. Lots of them are running on Linux but they still have closed-source code/drivers for some chips on their board.

You can find more information on the GPL license in the official FAQ.

Hi @sdk. Thank you for sharing your insights. It’s an interesting point you mentioned… however I am still highly in doubts (might it be different if this is an GPL-licensed “untouched” operating system or a “stand-alone” application using or deriving from GPL-licensed libraries?) I will try to investigate this further, personally.

Nonetheless, I still would love to get a response from a legal perspective, for instance Mozilla’s legal department Can anyone arrange for this?

I don’t think you’ll get a response from them here since they’re more an internal team. I mean you could be lucky if someone on the team is lurking on this forum.

However, maybe you could try to ask on or room on

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Great, will check it out. Thx.

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Maybe the commercial non-free software space for TTS solutions is already so saturated that there wouldn’t be much to gain for Mozilla to fight in this niche. In my humble opinion, the open web would benefit more from software that has to stay open than it would benefit from software that can be hidden as closed source.