Zaplit

Inspiration

We found ourselves multiple times in situations where one of us paid in fiat, and the rest of the group sent sats to that person. But the payer had to save the bills, do the math later, and report how much each person owed.

So we thought it would be great to have something like Splitwise but connected to Lightning.

What it does

Zaplit allows you to create a group, log shared expenses, and split them among members. It then collects payments directly from their Lightning wallets.

How we built it

Zaplit is a purely peer-to-peer solution. No middlemen, just instant payments via Lightning. Here’s what makes it special:

Nostr for coordination: We use Nostr events to handle team creation, bill tracking, and payment status—all encrypted and private.
Lightning for payments: Each user connects their NWC-compatible wallet, making payments instantly.
Client-side calculations: All payment splits, status updates, and balances are handled locally. We built the app using React, with a Nostr-based backend and NWC integration for payments.

Challenges we ran into

Using Nostr events as a data store: We had to design a way to update bill data and allow multiple participants to add expenses while maintaining a consistent state across the group.
Nostr Wallet Connect Integration: Since NWC is still evolving, we had to experiment with encryption and event handling.
Trustless bill splitting: Ensuring accurate payment tracking while keeping everything decentralized was tricky.
UX for non-Bitcoiners: We wanted Zaplit to be dead simple, even for people who aren’t Lightning experts. ## Accomplishments that we're proud of Creating a useful tool that we actually would definitely need in real life, specially this conference.

What we learned

We realized that we barely scratched the surface of what’s possible with Nostr + NWC, and we’re excited to keep pushing the limits.

What's next for Zaplit

We want to build a version where a single Lightning payment can automatically debit multiple accounts at once. Imagine splitting a bill in real-time—each participant’s share is deducted instantly as the payment happens.

We also plan to support multi-currency payments, allowing users to settle bills in their preferred currency while keeping everything Bitcoin-native under the hood.