Weak copyleft written as a delta on GPLv3. Consumer devices also owe installation information for a changed library.
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What it does
LGPL-3.0 is not a standalone license. It is a short set of additional permissions bolted onto GPLv3, so you read the two together. Qt's open-source edition is the best-known example. The relaxation is the same as in version 2.1: your closed application may link against the library. The copyleft duty, meaning changes go back out under the same license, stays on the library itself. The extra weight sits in section 4, which lists what a Combined Work has to carry. GPLv3 section 6 then adds Installation Information for consumer devices. If the library ships inside hardware a consumer buys, that buyer has to be able to install their own build of the library.
Details
For a hosted service, LGPL-3.0 asks nothing: there is no network clause and nothing is distributed. For shipped software it behaves like version 2.1 with one extra scenario. A router, a TV box, a car head unit or any locked consumer device drags in the Installation Information duty, and most teams have no plan for it. App store distribution is the argument you will hear next. The relink and installation requirements are widely read as hard to satisfy under the store terms, but that reading is not settled. Take that question to counsel before you build on it.
Pros
- You can link the library from closed code in the way the license describes.
- File-level reciprocity is easier to isolate than GPL-style whole-work copyleft.
Cons
- Vendoring or statically linking can pull more of your tree into the covered set than a dynamic link would.
- The source-offer duty is real the moment you distribute binaries that include modified covered files.
What it allows and requires
Choose a category to see the full grant in one scannable list. Permissions show what the license allows, limits show what it withholds, and obligations show the conditions your release process must satisfy.
Permissions
Commercial use
You may ship the code inside a paid product. The license does not restrict commercial use.
Modify
You may change the code, including keeping those changes private, unless a later obligation says otherwise.
Distribute
You may give copies to others. Distribution is what usually turns notice and source duties into real work.
Private use
Use inside your company, including internal forks, does not by itself trigger distribution duties.
Patent use
These licenses typically include a patent grant covering the licensed files. Read the grant before relying on it in a high-stakes deal.
Limits
Hold liable
The authors disclaim warranty. Recipients cannot hold them liable for damages arising from the software, except where law forbids that disclaimer.
Use trademark
The license is not a trademark license. Names, logos and product marks stay with their owners unless a separate grant says otherwise.
Open your product
File- or library-scoped copyleft does not, on its face, force you to open your entire application. Reciprocity stays on the covered files.
Obligations
Include copyright
Keep copyright notices on the covered files you distribute.
Include license
Keep the license text with the covered files, and say that those files are under this license.
Disclose source
Source for the library, including your modifications to it, has to be available to people who received a binary.
Keep replaceable
Recipients must be able to swap in their own build of the library. Dynamic linking is the usual path. Static linking means you also hand over a way to relink.
Installation Information
Or later still carries GPLv3 Installation Information on a User Product. Recipients may also take a future LGPL from the FSF.
What LGPL-3.0-or-later requires when you ship
When you distribute a binary that includes LGPL-3.0-or-later code, notice still travels with the copy, and the corresponding source has to be available under the same license. Internal use without a copy leaving the company is a different situation. The list below is the shipping work: what a recipient of that binary can demand, and what you record so a buyer can see it.
You are meeting section 4 when your Combined Work names the library, ships the LGPL and GPL texts, and shows the copyright notices where a user can see them.
You are meeting the relink condition when the library loads at run time as a separate file, or when you supply object code that lets a user rebuild the combination.
You have handled a consumer device when the buyer gets the Installation Information needed to put their own build of the library on the hardware they bought.
You have covered the source duty when everyone who receives your binary can obtain the library's complete source under the LGPL, from a public URL or a written offer.
You have dealt with your own edits when every change you made inside the library goes back out under the LGPL when you distribute it, separately from your application code.
The duties named in LGPL-3.0-or-later
Notice still travels with the copy. On top of that, LGPL-3.0-or-later names a source duty. These are the conditions in the text. The how-to above is when they become real work.
Include copyright
Keep copyright notices on the covered files you distribute.
Include license
Keep the license text with the covered files, and say that those files are under this license.
Disclose source
Source for the library, including your modifications to it, has to be available to people who received a binary.
Keep replaceable
Recipients must be able to swap in their own build of the library. Dynamic linking is the usual path. Static linking means you also hand over a way to relink.
Installation Information
Or later still carries GPLv3 Installation Information on a User Product. Recipients may also take a future LGPL from the FSF.
Things to be aware of
- Firmware teams sign the image and lock the bootloader, which defeats the Installation Information duty. Decide the license question before the hardware design is frozen.
- Teams treat LGPL-2.1 and LGPL-3.0 as the same license. They differ exactly where it costs money: consumer hardware, and mixing with GPLv2-only code.
- An iOS build static-links the library and ships with no relink path. Ship a dynamic framework, or pick a differently licensed library before the release branch.
What the GNU LGPL v3.0 or later does not do
Search results often flatten GNU LGPL v3.0 or later into a slogan. These are the usual misreads. LGPL-3.0-or-later is a grant with conditions, not a permission to skip the paperwork below.
- LGPL-3.0-or-later does not force you to open your whole application. The reciprocal duty stays on the covered files.
- It is not "permissive with extra paperwork." Change a covered file and ship it, and that file's source has to be available under the same license.
How LGPL-3.0-or-later differs from nearby licenses
These licenses are often confused with LGPL-3.0-or-later, but their release duties differ. Each row summarizes what the license requires when you ship. Open the linked page for the full checklist.
- LGPL-3.0-or-later
- Weak copyleft written as a delta on GPLv3. Consumer devices also owe installation information for a changed library.
- LGPL-3.0-only
- LGPL-3.0-only is library copyleft pinned to version 3. Same replaceability rule, with GPLv3 patent and User Product terms, and no later LGPL.
- LGPL-2.1-or-later
- Weak copyleft for libraries. Your own code can stay closed as long as users can swap in their own build of the library. Static linking makes relinking costly.
- GPL-3.0-only
- GPL-3.0 keeps the source duty on distributed binaries and adds a patent grant, an anti-lockdown rule for consumer devices, and a cure period.
Common questions about GNU LGPL v3.0 or later
Answers to common questions about what GNU LGPL v3.0 or later requires, when its duties apply, and what evidence belongs with a release.
What is the GNU LGPL v3.0 or later?
LGPL-3.0 is not a standalone license. It is a short set of additional permissions bolted onto GPLv3, so you read the two together. Qt's open-source edition is the best-known example. The relaxation is the same as in version 2.1: your closed application may link against the library. The copyleft duty, meaning changes go back out under the same license, stays on the library itself. The extra weight sits in section 4, which lists what a Combined Work has to carry. GPLv3 section 6 then adds Installation Information for consumer devices. If the library ships inside hardware a consumer buys, that buyer has to be able to install their own build of the library.
What does LGPL-3.0-or-later require when you ship a product?
You are meeting section 4 when your Combined Work names the library, ships the LGPL and GPL texts, and shows the copyright notices where a user can see them. You are meeting the relink condition when the library loads at run time as a separate file, or when you supply object code that lets a user rebuild the combination. You have handled a consumer device when the buyer gets the Installation Information needed to put their own build of the library on the hardware they bought. You have covered the source duty when everyone who receives your binary can obtain the library's complete source under the LGPL, from a public URL or a written offer. You have dealt with your own edits when every change you made inside the library goes back out under the LGPL when you distribute it, separately from your application code.
Does hosting a product that uses LGPL-3.0-or-later trigger extra duties?
Hosting alone usually does not trigger the source duty for LGPL-3.0-or-later. Shipping a binary, a container, or an on-prem build does. Notice still travels with any copy you hand over.
Can I keep my application closed if I use LGPL-3.0-or-later?
LGPL-3.0-or-later is library-scoped copyleft. Your application can stay closed if recipients can replace the library with their own build. Static linking makes that expensive. The library itself still ships with corresponding source and notices. Confirm the linking story on the component, then record it.
What is corresponding source for LGPL-3.0-or-later?
Corresponding source is the source a recipient needs to build and run the same binary, including scripts and interface files the license names. Hosting a repository URL can be an offer. The offer has to match what you actually shipped. SourceTrust records that a person on your team confirmed the offer. It does not publish your source and does not host a mirror.
How is LGPL-3.0-or-later different from GNU LGPL v3.0 only?
LGPL-3.0-or-later asks this: Weak copyleft written as a delta on GPLv3. Consumer devices also owe installation information for a changed library. GNU LGPL v3.0 only asks this: LGPL-3.0-only is library copyleft pinned to version 3. Same replaceability rule, with GPLv3 patent and User Product terms, and no later LGPL. Open the GNU LGPL v3.0 only page for what that license requires when you ship. Do not treat the SPDX ids as interchangeable because the short names look similar.
Where do I record LGPL-3.0-or-later for a buyer?
SourceTrust treats every SPDX id that starts with LGPL the same way. The catalog marks it as copyleft, so a source offer item lands on the project checklist in the Distributed binary and Mixed contexts. An LGPL linking item lands in Library or SDK, Distributed binary and Mixed. Both wait for a person to confirm them, and publishing is blocked until that happens. Nothing here decides your linking model or inspects your device build. If you ship an app store binary,
Where do I record LGPL-3.0-or-later for a buyer?
SourceTrust treats every SPDX id that starts with LGPL the same way. The catalog marks it as copyleft, so a source offer item lands on the project checklist in the Distributed binary and Mixed contexts.
An LGPL linking item lands in Library or SDK, Distributed binary and Mixed. Both wait for a person to confirm them, and publishing is blocked until that happens.
Nothing here decides your linking model or inspects your device build. If you ship an app store binary, read /docs/mobile-app-licenses for the distribution context and the in-app notice screen.
See also
The hub is the pillar for this cluster. Sibling licenses are the other spokes. Product FAQ links explain how SourceTrust records the duty, not the license text itself.
Practical guidance for procurement review, not legal advice. Confirm high-stakes use with counsel.