GPL and Lesser GPL libraries usage in commercial products

If you’ve created a product which you intend to sell (very small scale, think local) which is using GPL and LGPL libraries within the software running the product, whats the best method to “make available” the license document to the users of the product?

My interpretation of these license is that you must supply and acknowledge the use of “open source” software to users.

Is the inclusion of a URL to the licences document and acknowledgement of LGPL and GPL library use within the product GUI (think touch screen) enough? Or do I need to do more

Thanks in advance.

Usually the acknowledgement of the library and a clear mention of the (L)GPL together with a URL where to find it is enough to fulfill the basic requirements. But don't forget: if you use any GPL code you have to provide the complete source code of your project to all customers without restrictions. It's not enough to provide access to the libraries you used, all your code automatically gets GPL licensed too. This is usually no problem if the product you sell is mostly consisting of hardware but it might get a problem if you intend to primarily sell the software. Although it's allowed to sell GPL software, the availability of the source code to the customers (who might share it with everybody they like) makes a bad business plan if your business depends on selling software.

My interpretation of GPL is that you only need to provide source code if modifications to the library have been made?

How do you go about using GPL libraries in products then? Contact the authors?

If it's a GPL library (not LGPL) then all of your code falls under GPL. If it's a LGPL library then your code does not fall under GPL, but you must still release any modifications you made to the LGPL library itself. You're also required to release your code which links the LGPL library in an object form so it can be relinked, but in actual practice I'd expect those occurrences to be rare and you'd probably handle them on a case by case basis.

And yes, if you want to use a GPL library (and not have your code subject to GPL terms) then you can still contact the author for licensing.

I just double checked the licenses of the libraries im using and they actually all fall under LGPL or have no stated license with them which is a relief.

They include a number of Arduino libraries such as Time, EEPROM, SD, SPI, WIRE which are all LGPL acording to the Arduino FAQ (where as the hardware is GPL) as well as an LGPL LCD touch screen library called ITDB02_Touch and an LCD controller library which the version im using (2.0) was released under LGPL so looks like im in the clear :slight_smile:

No modifications were needed to any of the libraries, and in terms of linking code which links the LGPL library in object form for re linking...well im not exactly sure how/when/why that would come out so if anyone EVER did contact me about it I would do my bets to accommodate the request.

If anyone would clarify in practical terms what Chargrin meant by "release your code which links the LGPL library in an object form so it can be relinked" that would be great!

...or have no stated license with them which is a relief.

At least in the U.S., no stated license is not a relief. Without a license or permission from the copyright holder you cannot use it.

And if your not in the US?

Ill try contacting the authors, thanks for picking up on that!