Hey everyone! 👋 I’m the creator of Passbion, and I’m excited to share it with the community today. Why I built this: Whenever I looked up a financial or mortgage calculator online, I ran into the same two frustrations: The math is a black box: Most sites show you a single estimated payment or tax number with zero explanation of how they arrived at it. Aggressive lead-gen: Many tools hide results behind email opt-ins, phone number forms, or walls of third-party loan broker ads. I wanted something clean, transparent, and built with developer-first principles: a collection of financial calculators that explicitly show their math. What makes Passbion different: 📐 Explicit Formulas on Every Page: Every single calculator shows the full mathematical equation rendered cleanly in LaTeX, along with a worked, step-by-step arithmetic example. 🔒 100% Client-Side Privacy: Everything runs entirely in your browser using Next.js and React. No financial inputs, loan balances, or income numbers are ever sent to a server. ⚡ Zero Gating: No email signups, no paywalls, and no forms standing between you and the full amortization or payoff schedules. 🛠️ Real-World Edge Cases: Tools cover real-world nuances like FHA 3–4 unit self-sufficiency tests, 1099 self-employment quarterly tax breakdowns, and Debt Avalanche vs. Snowball payoff curves. I’d love to hear your feedback on the UX, formula clarity, and any specific financial tools or calculation edge cases you’d like to see added next!

Passbion

Financial calculators that show their math and formulas

Financial calculators that show their math and formulas