# Catalyst.jl and ModelingToolkit (question after reading about ModelingToolkit license changes)

**URL:** <https://discourse.julialang.org/t/catalyst-jl-and-modelingtoolkit-question-after-reading-about-modelingtoolkit-license-changes/135303>\
**Category:** Modelling & Simulations\
**Tags:** question, licenses, modelingtoolkit, catalyst\
**Created:** [January 28, 2026, 2:00am UTC](https://discourse.julialang.org/t/catalyst-jl-and-modelingtoolkit-question-after-reading-about-modelingtoolkit-license-changes/135303 "2026-01-28T02:00:47Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![twcawm](https://avatars.discourse-cdn.com/v4/letter/t/b782af/32.png) [@twcawm](https://discourse.julialang.org/u/twcawm)\
**Post date:** [January 28, 2026, 2:00am UTC](https://discourse.julialang.org/t/catalyst-jl-and-modelingtoolkit-question-after-reading-about-modelingtoolkit-license-changes/135303/1 "2026-01-28T02:00:47Z")

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Hi,  
I have been investigating and trying out the Catalyst.jl package (it’s really awesome, by the way!). I saw recently the discussions on ModelingToolkit license changes. Is the plan to keep maintaining Catalyst.jl as a totally MIT licensed package? Is there any guidance or elaboration you could give on how the ModelingToolkit license changes may currently or ever affect Catalyst.jl?

apologies if this is a naive question.  
[ModelingToolkit V11 Library Split and Licensing, Community Feedback Requested - #19 by isaacsas](https://discourse.julialang.org/t/modelingtoolkit-v11-library-split-and-licensing-community-feedback-requested/134396/19)

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**Author:** ![isaacsas](https://avatars.discourse-cdn.com/v4/letter/i/f6c823/32.png) [@isaacsas](https://discourse.julialang.org/u/isaacsas)\
**Post date:** [January 28, 2026, 4:06am UTC](https://discourse.julialang.org/t/catalyst-jl-and-modelingtoolkit-question-after-reading-about-modelingtoolkit-license-changes/135303/2 "2026-01-28T04:06:51Z")

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Yes, Catalyst will stay MIT. Our understanding is that MTKBase is supposed to support all the functionality that Catalyst previously relied on, and we are currently updating it for use with MTKBase.