OpalCalc is described as 'Brand new type of calculator for the PC. As easy to use as Notepad or a word processor, OpalCalc allows natural language in the sum and multi-line support so you can go back and adjust your previous calculations on the fly' and is a Calculator in the education & reference category. There are more than 50 alternatives to OpalCalc for a variety of platforms, including Windows, Linux, Mac, Web-based and Android apps. The best OpalCalc alternative is SpeedCrunch, which is both free and Open Source. Other great apps like OpalCalc are Qalculate!, Numara Calculator, Numbat and Qaltex.
Kalk is a convergent calculator application built with the Kirigami framework. Although it is mainly targeted for mobile Linux platforms, it can also be used on the desktop.
Germany
EU
Hissab is a simple and intuitive calculator, unit-convertor and productivity application.
Numby transforms how you calculate. Express math naturally, convert units and currencies, track your work, and share results beautifully - all in one place.
Hong Kong SAR China
A text calculator for natural language expressions, variables & unit conversions, with a vim-style TUI. Inspired by Numi.
Omni Calculator is a web/mobile calculator that solves concrete problems such as mortgage payment, gross margin, body mass index, break-even point, etc. It's very user-friendly, flexible and usable on web, mobile and as an embeddable web widget.
PolandEU
Ever wanted to work something out, but your default calculator isn't powerful enough, and it's not worth creating a spreadsheet for?
The Unsure Calculator is an online tool that lets you calculate with numbers you’re not sure about.
CzechiaEU
Numbr is a currency calculator, a notepad that understands your calculation. You can use notes with numbers alongside each other. And all your numbers are instantly calculated as you type.
HungaryEU
Calculist is an open source application that facilitates effective thinking. Write down your thoughts, ideas, and data in the form of lists. Focus your attention by zooming in to a specific list, and zoom out to see the broader context.
A kickass, open-source calculator that lets you do calculations and unit conversions naturally, with features like:
