# Using the Processing core library in .jar format in my now-MIT-licensed Java program

**URL:** <https://discourse.processing.org/t/using-the-processing-core-library-in-jar-format-in-my-now-mit-licensed-java-program/46066>\
**Category:** Processing\
**Created:** [March 25, 2025, 1:38pm UTC](https://discourse.processing.org/t/using-the-processing-core-library-in-jar-format-in-my-now-mit-licensed-java-program/46066 "2025-03-25T13:38:05Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![LangdonS](https://avatars.discourse-cdn.com/v4/letter/l/ebca7d/32.png) [@LangdonS](https://discourse.processing.org/u/LangdonS)\
**Post date:** [March 25, 2025, 1:38pm UTC](https://discourse.processing.org/t/using-the-processing-core-library-in-jar-format-in-my-now-mit-licensed-java-program/46066/1 "2025-03-25T13:38:05Z")

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I have a Java program that used the Processing core.jar as a library to function.

I want to use the MIT license.

How do I license this properly?

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**Author:** ![sableraph](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/sableraph/32/251_2.png) [@sableraph](https://discourse.processing.org/u/sableraph)\
**Post date:** [March 25, 2025, 2:05pm UTC](https://discourse.processing.org/t/using-the-processing-core-library-in-jar-format-in-my-now-mit-licensed-java-program/46066/2 "2025-03-25T14:05:29Z")

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Hi @LangdonS and thanks for your question.

You can license your own code under MIT while using Processing’s `core.jar` (LGPL 2.1), as long as:

- You **don’t modify** `core.jar`.
- You **dynamically link** `core.jar` (e.g., keep it as a separate `.jar` or use it as a [Maven dependency](https://central.sonatype.com/artifact/org.processing/core)).
- You **include the LGPL 2.1 license** and inform your users that your software links an LGPL-licensed component.
- You **make it possible for users to replace** `core.jar`, if they choose.

This lets you keep your code under MIT while respecting LGPL requirements.

Please also consult the full [LICENSE.md](https://github.com/processing/processing4/blob/main/LICENSE.md) for more details as some other licenses may apply to Processing core dependencies.

Note that **I am not a lawyer** or a licensing expert and that **this is not legal advice**.

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**Author:** ![LangdonS](https://avatars.discourse-cdn.com/v4/letter/l/ebca7d/32.png) [@LangdonS](https://discourse.processing.org/u/LangdonS)\
**Post date:** [March 25, 2025, 3:41pm UTC](https://discourse.processing.org/t/using-the-processing-core-library-in-jar-format-in-my-now-mit-licensed-java-program/46066/3 "2025-03-25T15:41:33Z")

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" …inform your users that your software links an LGPL-licensed component."

What do you mean exactly?

In the LICENSE file (the one with the MIT license)?

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<div class="post-metadata">

**Author:** ![sableraph](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/sableraph/32/251_2.png) [@sableraph](https://discourse.processing.org/u/sableraph)\
**Post date:** [March 25, 2025, 3:55pm UTC](https://discourse.processing.org/t/using-the-processing-core-library-in-jar-format-in-my-now-mit-licensed-java-program/46066/4 "2025-03-25T15:55:59Z")

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The LGPL doesn’t prescribe exactly _how_ to do it, just that you must give a “prominent notice” that your software uses the Library and that it’s covered by the LGPL.

In Section 6 it says:

> _You must give prominent notice with each copy of the work that the Library is used in it and that the Library and its use are covered by this License._

Note that this is a separate requirement from including a copy of the full license text.

For a clear summary of LGPL 2.1 requirements, see: [GNU Lesser General Public License v2.1 (LGPL-2.1) Explained in Plain English - TLDRLegal](https://www.tldrlegal.com/license/gnu-lesser-general-public-license-v2-1-lgpl-2-1)

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<div class="post-metadata">

**Author:** ![LangdonS](https://avatars.discourse-cdn.com/v4/letter/l/ebca7d/32.png) [@LangdonS](https://discourse.processing.org/u/LangdonS)\
**Post date:** [March 25, 2025, 4:43pm UTC](https://discourse.processing.org/t/using-the-processing-core-library-in-jar-format-in-my-now-mit-licensed-java-program/46066/5 "2025-03-25T16:43:57Z")

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How’s this?:  
“This app makes use of the Processing core library, licensed under the LGPL v2.1”