Chip-In

Say "get us a Switch for the office, split 6 ways." The agent sends PayPal QR invoices to everyone, tracks who paid, places the order the moment it's funded, and refunds all if it isn't.

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Inspiration

Every group has one person who fronts the money. The office gift, the shared console, the holiday house deposit, the team jersey order. That person chases five people for weeks, eats the shortfall when someone forgets, and has no clean way to refund everyone if the plan falls through. Group buying is a universal human ritual with no good product behind it. We wanted an agent you could just talk to: it collects, it waits, it buys, and it refunds, with PayPal doing the money every step of the way.

What it does

You tell Chip-In what the group wants and how to split it: "Get us a Nintendo Switch for the office game nights, split six ways between these people." The agent then:

  • Finds the item and price (via Channel3 product search) and proposes a plan: total, per-person share, deadline.
  • Issues a PayPal invoice to each contributor, each with a QR code so people can pay from their phone in one scan, and sends them out.
  • Tracks payments as they land, nudges the stragglers with invoice reminders, and keeps a live funding bar everyone can see.
  • The moment the pot is fully funded, creates and captures a PayPal Order for the item and attaches shipment tracking so the group can follow the parcel.
  • If the deadline passes short, it refunds every contributor automatically, so nobody is left holding other people's money.
  • Answers questions along the way: "who hasn't paid?", "can we add a seventh person?", "what if we cancel?" and recalculates shares live.

The organiser's view uses AG Grid for the contributor ledger.

How we built it

  • Next.js 15 + TypeScript on Vercel.
  • PayPal Agent Toolkit for Invoicing v2 (create_invoice, send_invoice, generate_invoice_qr_code, send_invoice_reminder, record_payment_for_invoice, list_invoices), Orders (create_order, pay_order, get_order), Refunds (create_refund) and Shipment Tracking (create_shipment_tracking).
  • PayPal Webhooks for INVOICING.INVOICE.PAID so the funding bar updates in real time and the buy triggers the instant the last share lands.
  • Claude (Anthropic API) turns the request into a validated group-buy plan (item, participants, split, deadline), writes the contributor messages, and runs the chat assistant with the Agent Toolkit as its tools. The model proposes; deterministic code checks the arithmetic and executes.
  • Channel3 product search API for finding the item and price.
  • AG Grid for the contributor ledger.

Challenges we ran into

Splitting amounts that don't divide evenly (and explaining it). Making the "fully funded, buy now" moment race-free when two people pay at once. Designing the refund path so it is always possible, even halfway through.

Accomplishments that we're proud of

A complete collect-wait-buy-or-refund loop that runs on PayPal invoices, orders and refunds, triggered by a single sentence.

What we learned

QR-code invoices are the fastest way to get a group of non-technical people to pay. The hard part of agentic commerce is the state machine, not the model.

What's next

Recurring group buys (monthly shared subscriptions), partial-contribution tiers, and a shareable public page per pot.

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