I built Finikit — 33 free financial calculators in 5 languages, all running in your browser
I wanted a compound interest calculator without ads, without signups, and without my data being sold. Couldn't find one I liked, so I built my own — and then kept going.
6 weeks later: finikit.com has 33 calculators covering investing (compound interest, FIRE planner, ROI, CAGR), loans(mortgage, car loan, credit card payoff), savings (emergency fund, inflation, net worth), and more.
Stack: pure HTML/CSS/JS on Vercel. Zero dependencies. Zero backend. Works offline.
5 languages: English, Chinese, Japanese, Spanish, Korean.
What surprised me: the "reverse compound interest calculator" (solve for required rate) is a blue-ocean keyword with almost zero competition. Sometimes the best growth hack is just building what people are searching for.
Would love feedback from the IndieHackers community — especially on the multi-language setup and calculator UX.
The part that caught my attention wasn't the calculators.
It was the "and then kept going."
A lot of utility products start with one thing people genuinely need.
The interesting question is usually what earns the right to become calculator #2, #10, or #33.
Curious how you're deciding which additions make the product stronger versus just larger.