The modern Smalltalk-80

Cuis is a free Smalltalk-80 environment with a specific set of goals: being simple and powerful.
It is also portable to any platform, fast and efficient.

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The Cuis Smalltalk development environment — A typical work-in-progress scene in Cuis Smalltalk application development: An Inspector displays an object from the running application, a message is sent to this object to show its halo, and the auto-completion tool is active. Class browsers are open on the application’s relevant classes; a Transcript provides feedback on the application’s execution; under the application view, a Workspace contains code related to the application.

“I like it… It’s nice and clean and simple and pretty. Nice stuff!”

Alan Kay

“Yay, Juan. You GO, guy! …a great example of malleable software (and a clever mind) at work.”

Dan Ingalls

“I think you have a very elegant design aesthetic.”

John Maloney

Latest news

2026-10-01
Cuis at Smalltalks 2026

Smalltalks 2026 takes place from October 14 to 16 at the Facultad Regional Rosario of the UTN, in Rosario, Argentina, and Cuis will be there: eight talks of the program come from the Cuis community or show work done in Cuis. We hope to see you all there!
2026-06-02
July Cuis Meeting

What. It is a “Demo Meeting” for demonstration then discussion. Milan Lajtos will present his experience on using a code agent to develop Blueprint, a revisit of the Cuis Smalltalk system desktop.
2026-06-01
Cuis 7.8 release

Cuis 7.8 stable release!

Older news

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Latest meeting

Blueprint

Blueprint is a rework of the Cuis Smalltalk system desktop done purely by a code agent (artificial intelligence) directed in natural language, no Smalltalk code was written by hand.

Milan Lajtos
2026-07

Past meetings

The modern Smalltalk-80

Latest news

Cuis at Smalltalks 2026

July Cuis Meeting

Cuis 7.8 release

Latest meeting

Blueprint