I have some doubts about the sozu proxy that is under AGPL license. If I use the sozu binary as a proxy for my products (API, WebApp, etc.) without any mods or extensions, should I release my products also under the same license or can I leave them privately licensed?

  • Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.
    – Community Bot
    Mar 23, 2023 at 15:08

1 Answer 1


You can probably use the software.

The AGPL-3.0 is exactly equivalent to the GPL-3.0, except for section 13 which only applies “if you modify the Program”. You have not modified the AGPL-covered program. Thus, you can treat it as effectively GPL-3.0-covered.

The GPL-3.0 license would not require you to publish your code just because you use GPL-3.0 covered programs on your backend.

However, if you were to modify Sozu, or were to incorporate parts of Sozu code into your software, then running this modified Sozu software on your backend would trigger AGPL section 13, and you would have to offer your users the source code for the modified Sozu version (but not the source code for other programs you're using on your backend).

So the AGPL is entirely unproblematic for separate services that you use on your backend without modification. Back when MongoDB was still AGPL-licensed, people used it without blinking an eye. The situation is not materially different for a reverse proxy. But if you're concerned about this, use a different reverse proxy under a more permissive license, for example Nginx (Open Source edition).

  • Thanks for the answer, I guess it's ok to use as long as the binary is used and nothing is changed.
    – Juli4nDev
    Mar 23, 2023 at 17:59
  • 1
    If the OP incorporates parts of Sozu in their software, then that software needs to be released under the AGPL license as well, not just Sozu. Mar 24, 2023 at 9:05
  • @BartvanIngenSchenau, some more info about aggregate vs derived work: gnu.org/licenses/gpl-faq.html#MereAggregation Mar 24, 2023 at 10:44
  • @akostadinov, I know about mere aggregation, but that does not appear to be what this answer is referring to. If amon was referring to an aggregated distribution, then that should be clarified. Mar 24, 2023 at 13:37
  • I don't intend to incorporate parts of sozu into my software or modify it, I'll take the binary and configure it like apache 2 or nginx.
    – Juli4nDev
    Mar 24, 2023 at 20:12

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