Frequently asked questions
These answers summarize the license for convenience. The license text (TPL 2.3) is authoritative in case of any difference. Section references link into the full text.
May I use TPL-licensed material commercially?
Yes. The grants are universal and field-of-use neutral: commercial use, modification, and redistribution are expressly permitted (Section 2). You may charge for distribution and for services, support, maintenance, or warranties — provided you do not misrepresent the material as proprietary, do not restrict recipients' rights, and disclose clearly when you charge for the Licensed Material itself, which remains free of charge under the license (Section 5.10).
Do I have to release the source code of my changes?
No. TPL is permissive and contains no copyleft: nothing requires you to license, publish, disclose, or release the source code of your Derivative Works or User Works under this license or any other (Section 4.3). You only need to satisfy the notice and attribution conditions in Section 4.
What is a "User Work"?
A work that you author for or with the Licensed Material — for example, a program written in a language distributed under TPL, or an application built on a TPL-licensed library (Section 1.7). User Works are your own works: no license conditions attach to them, and no attribution, notice, or license text is required in them, unless they incorporate or reproduce Licensed Material source code (Sections 4.1, 4.2).
Can I train AI or machine-learning models on TPL-licensed material?
Yes. Reproducing the Licensed Material to train, fine-tune, evaluate, or otherwise improve a model is a use and reproduction permitted under Section 2 (Section 4.4(a)). The model's weights, parameters, and other learned artifacts are not Object Form, not Derivative Works, and not Licensed Material (4.4(b)). Output generated by the model is a User Work of whoever generates it, regardless of training data (4.4(c)), and no attribution or license obligation attaches to outputs by reason of training alone (4.4(d)). The one caveat: to the extent an output incorporates or reproduces Licensed Material source code, that portion remains subject to Section 4.
I run the material as a hosted service. What must I do?
Make the copyright notices, and either a copy of or a direct reference (such as a URL) to the complete license text, readily accessible to your users — for example in the documentation, an "about" page, or the terms of service (Section 5.8). Nothing in Section 5.8 obliges you to disclose the source code of the service.
Where must notices appear in an end-user product?
Notices must be reasonably conspicuous and accessible to recipients — for example in an "About", "Credits", or "Legal Notices" section. Placement solely in machine-readable files or installer logs does not satisfy this for products distributed to end users (Section 5.9).
Can I use the TIE name or logo to promote my project?
Not without prior written permission. The Licensor's name and Brand Mark may not be used to endorse or promote works derived from the Licensed Material, except where the law provides for such use in a non-confusing manner (Section 8). Stating factually that your project uses TPL-licensed material is different from implying endorsement.
My distribution bundles third-party assets. What applies to them?
Their own licenses. Third-party material is identified and governed by its separate terms (Section 6.1); you must comply with those terms (6.2), retain third-party notices and license texts (6.3), and not remove or misrepresent them (6.4).
Which version of TPL applies to a given work?
The version stated in the work's LICENSE file or notice. Works distributed under TPL 2.0, 2.1 or 2.2 remain governed by those versions; the current version is TPL 2.3. New adoptions should use the current version.
Who governs disputes?
In the absence of an effective Designation, the license is governed by the law of the Licensor's domicile, and disputes go to the competent courts there (Sections 12.1, 12.2). A Licensor may designate a specific governing law and/or venue by a plainly identified Designation in the LICENSE or notice file. Mandatory local law prevails where it cannot be excluded (12.4).