License for using JUCE utilities

I want to use JUCE’s audio format utilities outside of the traditional JUCE environment, i.e. to grab a few JUCE cpp files to perform audio file parsing for various audio formats, and add them as is into my project (eventually a commercial product).

No Projucer involved, no autogenerated code. Only taking a few previously-generated files and using them for the described purpose.

I have a proof of concept working great.

What is the license needed for that?

It sounds like you’re using code from the juce_audio_formats module. The code in this module is dual-licensed under the JUCE 6 End User License Agreement and under the GPL v3. If you want to avoid making your code open-source, you must use the JUCE 6 license.

The JUCE 6 license has several tiers. Details of these tiers can be found in the license, linked above. The tier you should use will depend on the revenue generated by your company. Some tiers also require a “Made with JUCE” splash-screen to be displayed in your application. To avoid displaying the splash screen, you will need either the “Indie” or “Pro” tier.