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Plus42 vs kalker: catalog facts
Plus42	kalker
Free Desktop builds are free and open source under GPL-2.0; mobile store pricing is not stated.	Free Free and open source under the MIT licence.
Windows, macOS, Linux, Android, iOS	Windows, macOS, Linux, Android, Web, Command line
Faithful HP-42S behaviour with modern additions Plotting, units and TVM built in	Natural math syntax with user-defined functions and variables Handles complex numbers, vectors and matrices
RPN workflow takes time to learn Aimed at HP calculator users rather than casual use	Derivatives and integrals are numerical estimates Higher-order derivatives can be inaccurate
Downloadable app	Downloadable app, Web application
Open source	Open source
License: GPL-2.0	License: MIT
No account needed	No account needed
Works offline	Works offline
Official website Full listing and sources Checked October 2, 2026	Official website Full listing and sources Checked October 2, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.