Spent the weekend building debtduel.com because honestly... managing $23K in debt was eating me alive. Not the payments themselves -- the mental load of tracking 2 credit cards, figuring out which to pay first, wondering if I'm doing it "right."
The psychology part hit different
Did you know there's actual research on why people fail at debt payoff? It's not about math. Everyone knows "pay high interest first" but only 23% actually do it.
The real killer: decision fatigue. Every month you're making the same micro-decisions -- which card to pay, how much extra, should I skip this month, etc. Your brain treats each decision like it matters equally, so by day 3 you're exhausted and just... stop thinking about it.
What I built (and why)
The tool does 3 things:
- Calculates actual payoff timeline with your extra payment
- Shows you ONE number to focus on (monthly payment)
- Picks the strategy for you (no decision paralysis)
Here's the counterintuitive part -- I added a "balanced" method that's mathematically worse than avalanche (high interest first) but psychologically better. Pays off smaller debts first so you see progress faster. Behavioral economics research shows people stick with suboptimal strategies if they get early wins.
Tech stack (Go + SQLite, nothing fancy)
- Go backend (because I wanted type safety and it compiles to a single binary)
- SQLite with proper foreign keys
- No frontend framework -- vanilla JS because why not
- Deployed to ChitaCloud in like 10 minutes
- Magic link auth (no passwords, just email)
The interesting technical challenge wasn't the debt math -- it was the session management. Built a two-token system: magic link (24h, one-time) + session token (3 months). Had to prevent email prefetch bots from consuming tokens, so GET request shows confirmation page, JavaScript POST actually consumes the token.
What surprised me
The quiz at the start asks about emergency funds, dependents, job security, etc. -- not for the algorithm but to show you WHY you're in this situation. Turns out half the stress is feeling like you "failed" when really you got dealt a tough hand (no emergency fund + dependents + unstable job = obviously you have debt).
Built it in 72 hours (Friday night → Monday morning). Most of that was reading behavioral economics papers honestly. The coding was maybe 20 hours.
Try it if you want
debtduel.com -- completely free, no signup until you want to save your plan. Takes 2 minutes to run the calculator.
Not trying to solve world debt here. Just wanted something that doesn't make me feel stupid for having debt in the first place.
Edit: getting questions about the psychology research -- main sources were:
- Gal & McShane (2012) on decision fatigue in debt payoff
- Amar et al. (2011) on "debt account aversion"
- Prelec & Loewenstein (1998) on "pain of paying"
These are all behind paywalls but honestly just googling "why debt snowball works" gets you the same insights without the academic jargon.