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IUP

Free#40 of 61 in Desktop App Development Frameworks

IUP: A free native UI toolkit for C and Lua desktop apps on Windows and Linux. Ranked #40 of 61 in Desktop App Development Frameworks by our editors (5.3/10); pricing: Free plan; best for C or Lua developers building Windows and Linux GUIs.

5.3/10Editor score

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IUP5.3 Visit IUP

At a glance

Editor score
5.3 / 10
Pricing
Free plan
Best for
C or Lua developers building Windows and Linux GUIs
Free plan
Yes
Paid from
Free
UI stack
Native
Facts checked
23 Oct 2026

Where it wins
- Free software usable in public and commercial applications
- Offers C, Lua and LED paths for building interfaces
- Includes native controls, layout tools and predefined dialogs
Where it doesn't
- Targets Windows and Linux rather than mobile platforms
- Regular development has been on hold since 2023
- Maintenance is limited to small bug fixes and changes

Our verdict on IUP

IUP is a free toolkit for building desktop graphical interfaces in C, Lua or LED. Its audience is developers who want controls, dialogs and layouts for Windows and Linux applications, particularly those working in C or Lua. The toolkit provides buttons, lists, text fields, menus and canvases, alongside tabs, a matrix control and an OpenGL canvas. Predefined dialogs cover file selection, messages and data input, giving projects common interface elements without requiring every dialog to be specified from scratch.

IUP's interface model combines native elements on supported platforms with an abstract box-and-glue layout system. Its backends include GTK+, Motif and Windows, and the toolkit is intended to let applications run across supported systems with minimal platform-specific changes. Developers can create and manipulate dialogs through the C API, use the Lua binding for UI development, or describe dialogs in LED. This mix suits teams that value those languages and a native desktop UI approach; it is a narrower fit for projects seeking mobile targets or a broader platform range.

The main qualification is the project's maintenance status: regular development has been on hold since 2023, with work limited to small bug fixes and changes and no timeline for a return. That makes IUP a more suitable consideration for developers comfortable evaluating a toolkit with limited ongoing maintenance than for teams that require active development or commercial support. It remains free software and can be used in public and commercial applications. Developers who need a C or Lua toolkit for Windows and Linux may find its control set and layout model relevant; those prioritizing regular development or mobile deployment should look elsewhere.

Your product? Our editors can test IUP in depth and publish a review, labelled as paid · from $149/mo →

IUP pricing

Plans Free planFree Free to use — no paid tier required for the core job.

See plans on tecgraf.puc-rio.br

IUP fact sheet

Free plan	Yes
Paid from	Free
Supported desktop OS	Multi_platform
UI stack	Native
Primary language	C
Open source	Yes
Mobile targets	No
App packaging	Not verified
Commercial support	No
Deployment	Desktop
Platforms	Windows, Linux
Support	Email, Community, Docs
Built for	Solo, Small business (editorial estimate)
Pricing	Free plan
Website	tecgraf.puc-rio.br
Facts checked	23 Oct 2026

Alternatives to IUP

See all IUP alternatives →

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The editor score above is our own research. What this page doesn't have yet is a reader's view — what you used IUP for, what worked and what didn't. No stars are seeded and no review is paid for; an editor reads every one before it appears.

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Featured on iTechGuides

IUP is listed in our Desktop App Development Frameworks directory. Add the badge to your site — it links back to this page.

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Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026

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Last updated 30 Oct 2026 · How we research and update