Work / Kubera

Kubera

Current version in daily use by my family since April 2026 · Opening to other households soon

A credit-card reward tool for a household. It answers one small question quickly: “Which card should I use here?”

Card rewards are easy to understand one card at a time and tedious across five. Points are worth different amounts, merchants belong to several categories at once, and monthly credits expire quietly. I was doing that arithmetic in my head at checkout, so I wrote it down once.

Search for a place, see every card ranked by what it is really worth there, then open a card to check whether it earns its fee.

Ask about a place, not a category

Type “restaurants”, “Costco” or “Whole Foods”. Kubera knows which categories a merchant belongs to and which cards earn where, and it values each program’s points instead of comparing raw multipliers. A 4× on one card and a 3× on another stop being guesses and become 4.4% and 3.5%.

It also surfaces credits that apply to the purchase, like a monthly dining credit you haven’t used yet.

Kubera ranking five cards for restaurants, from 4.40% to 2.00%.

Kubera home screen with wallet cards, annual value and expiring credits.

The wallet, at a glance

The home screen is the whole household’s wallet: which cards are active, what they are worth together after fees, and which credits are about to lapse this month.

Desktop home screen showing five cards, $426 annual value, 7 credits tracked and 4 expiring soon.

Is this card worth its fee?

Every card shows its annual fee next to the value it actually returned: credits used, perks you care about, and your own estimates where the default doesn’t fit. The tracking tab keeps the monthly and half-yearly credits honest.

Amex Gold card page: $325 fee, $424 estimated value, $99 net benefit, and earn rates.

Amex Gold tracking tab with available, used and expired credits.

A few years of history

Over time it becomes a record of what each card really gave back, year by year, which is the number I want when a renewal fee arrives.

History view with benefit value by card and year.

Under the hood

A reward engine, not a lookup table. Merchants and categories form a graph, so Whole Foods inherits from Groceries. Point values follow transfer chains between programs. Each purchase is priced by every route it could take, and the best one wins.
Built for a household. People share one wallet and can override a card’s fee or a program’s valuation without changing anyone else’s defaults.
Also on WhatsApp. Mitra, our family assistant, asks Kubera the same question through a small internal API, so the answer is a message away.
Plain parts. React and Vite on the front, Express, Prisma and PostgreSQL behind it, all in three Docker containers.

Screenshots and the recording use a demo household with sample cards and made-up usage. Kubera will open to other households soon.