CentNook makes clear calculators for the money side of small businesses and households: pricing with margin and markup, VAT, discounts, ROI, break-even and ad costs, savings with CDs and APY, and a barcode generator for products. Each tool explains the formula it uses and the numbers people often confuse, and everything runs in your browser, so your figures stay with you. The tools are not financial or tax advice.
How our tools work
Every tool on CentNook runs inside your web browser. When you open a file, your own device does the work using built-in browser technology and WebAssembly. Nothing is uploaded, so the tools are fast, work with large files, and keep your files private.
Free, without sign-ups
You'll never need an account or an email address. The site is paid for by ads, which we keep out of the way of the tools themselves.
Who we are
CentNook is built and maintained by BlueEra. We'd love to hear which tool you'd like next, or about anything that doesn't work: get in touch.
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Open-source software
CentNook is built with Preact, Lucide icons, Mona Sans font. Thank you to their authors. See the open-source licences for versions, source code and licence texts.