Free tools that get the math right
BoringStack builds free, accurate calculators for finance and health. No signup, no paywall, no data collection beyond basic analytics. Every calculation runs in your browser — we never see or store the numbers you enter.
What we make
We build single-purpose calculators that answer one question well. Each tool is designed to load fast, work on mobile, and show its math openly so you can verify the result yourself.
Who's behind this
BoringStack is an independent project run by Sami Vallin, based in Sweden. It's not a company with a team — it's one person who got tired of calculator sites buried in popups, and decided to build better ones.
The name is the thesis. The most useful corner of the internet isn't the flashy part — it's the boring calculator you Googled three years ago that just worked. That's what we're building more of.
How our calculators are built
Every tool follows the same standards:
- Published formulas. Each calculator shows the underlying formula so you can check the math by hand.
- Client-side only. Your inputs never leave your browser. Nothing is sent to a server or stored.
- Standard sources. Financial formulas follow standard amortization and compound interest math. Health categories follow World Health Organization classifications.
- Fast and mobile-first. Pages load in under two seconds and work on any screen size.
- No dark patterns. No email walls, no fake urgency, no interstitials before you see the result.
Editorial approach
Our written guides are researched and reviewed before publishing, and updated when the underlying facts change. We aim for accuracy over volume — fewer articles, checked properly.
We're explicit about limitations. A BMI calculator will tell you BMI is a screening tool, not a diagnosis. A mortgage calculator will tell you it excludes taxes and insurance. Being useful means being honest about what a number does and doesn't mean.
Not professional advice. Our tools are for information and education. They are not financial, medical, or legal advice. Consult a qualified professional before making decisions about your money or your health.
How we make money
BoringStack is free to use and funded by advertising and affiliate partnerships. When we display ads, they're clearly separated from the tools. When a link is an affiliate link, we label it as sponsored — you pay nothing extra, and it doesn't influence what we recommend.
We don't sell your data. We don't have your data. See our Privacy Policy for exactly what is and isn't collected.
Corrections and feedback
If you spot an error in a calculation, an outdated figure, or something unclear — tell us. Corrections get made quickly and we'd rather be right than look right.
Site details
- Operator: Sami Vallin, sole proprietor
- Location: Sweden
- Contact: hello@boringstack.io
- Founded: 2026
- Legal: Privacy Policy · Terms of Service