Why I Built 88 Financial Calculators
I'll be upfront about this: I didn't start Wanjaaro out of some grand mission. I started it because I wanted to make a few hundred extra dollars a month online, and eventually build toward some real financial freedom. That's it. That's the honest starting point.
I'd spent over a decade building backend systems for banks and insurers — mortgage underwriting, claims processing, compliance. I knew the math behind compound interest, amortization, tax brackets, retirement withdrawals cold. It was the one area where I could move fast and actually ship something without needing a co-founder, a design team, or funding. So I started building calculators.
The One Rule I Set for Myself
Early on I made a decision that shaped everything after it: the basic tools would never sit behind a signup or a paywall.
Not because I'm against making money — I'm very much trying to — but because I've used enough "free" calculators that ask for your email on step two to know how that feels. You want a number, not a lead-gen form. If someone just wants to know their monthly mortgage payment or how fast their debt snowball pays off, that answer should take five seconds, not an email verification.
So every calculator runs entirely in the browser. No account, no server round-trip, nothing typed ever leaves your device. Partly that's a privacy choice. But honestly, it's also just the simplest way to keep a promise: use it now, no strings.
Why Browser-Based, Practically Speaking
Beyond the principle, it made sense for someone building this solo:
No backend to maintain means I can spend my limited time writing calculators, not managing servers.
Instant results — no loading spinners, no API calls — makes the tools feel good to use, which matters when you're competing with sites that have real marketing budgets.
Trust without a sales pitch. I don't have to convince anyone their data is safe. It never left their browser in the first place.
Where the Money Comes From, Then
If the tools are free, this has to make money some other way — ads, affiliate links, maybe a premium tier down the line for things like saved scenarios or exports. I'm still figuring that part out, and I'd rather be honest about that than pretend this is a charity project. But the calculators themselves — the actual utility — stay free and open. That part isn't up for negotiation, because it's the whole reason anyone would come back.
Where It's Headed
More calculators, better explanations, and slowly building toward something that pays for the time I put into it — without ever making someone hand over their email just to do arithmetic.
If you're building something similar and want to compare notes on keeping tools genuinely free while still trying to make it sustainable, I'd love to hear from you.
The local-first approach is an interesting implementation choice, but I'd keep validating what people are actually adopting Client Koi for. The bigger opportunity may not be scraping Google Maps—it may be giving teams a reliable way to build outreach lists they trust without depending on expensive lead databases.
Really resonates, especially the "no signup, no paywall for the basics"
rule - I made the same call for PoliczNetto (calculators for Polish
freelancers comparing take-home pay across jobs, contracts, and running
a business). Same reasoning as yours: I've abandoned enough calculators
myself the moment they asked for an email just to show me a number.
One thing I did differently, and I'm curious how you think about it:
I went the opposite direction on scope. Instead of building toward 88
calculators, I deliberately stopped at 6 and spent the extra time on
long explanations, worked examples, and a methodology page for each
one - partly because my niche (tax/social security) is the kind where
being wrong erodes trust fast, and partly because as a solo dev I
couldn't maintain 88 of anything without either automating the content
or letting quality slide.
Did you think about that tradeoff before going wide? With 88 calculators,
how do you handle keeping the underlying rules/rates current across all
of them as a solo builder - is that mostly evergreen math, or do a lot
of them need periodic updates like tax brackets do for mine?
Dear, I have built few agents to handle design content. for the formulas and Tool UI, I have templated everthing. A single template handle multiple tools while building process. what I need just is input, output, history fields so every calculator on wanjaaro produce same user experience across the site. If you need to know anything, you can directly connect me and we can discuss ideas, implementation and so on