01Concept projectFintechConversational AI

Flow: banking that disappears

AI money tools for Gen Z that show up inside iMessage, Instagram and Uber at the moment someone is about to spend, instead of asking them to open a separate banking app.

My role: End to end: research, platform architecture, interaction design
Deliverables: 21-screen clickable prototype across all three products, architecture docs, React case-study site
Surfaces: iMessage, lock screen, widgets
Status: Concept, not built for production

Nine iPhone screens of the Flow Split flow, left to right: an iMessage group chat where Flow detects a $94.50 dinner bill and suggests a split; split details with Equal, Custom and Itemized options; Apple Pay confirming a $31.50 share; processing; split sent with $63.00 outstanding; live status at 2 of 3 paid with a nudge for the friend who hasn't opened it; a decline path with options to cover the share, nudge again or cancel; split settled; and a sheet of status chips and components. — Flow Split, end to end: from "total was $94.50, splitting 3 ways" in a group chat to a settled split. Scroll sideways to see every screen.

The problem

Friends already sort out shared costs in group chats. Then they leave the chat to pay in one app, check their balance in another, and save toward trips in a spreadsheet.

Banking apps show up after the money is spent. The decision itself happens somewhere else, and every switch is a chance to drop the task, forget who owes what, or overspend without noticing.

My approach

Instead of one more app, I designed three small tools that each appear at a specific moment: right after a shared bill, right before a purchase, and while a group plans a trip.

They sit on one shared layer, so each can pass the user to the next one at the right time. Every tool shows its suggestion, offers a choice, and gets out of the way.

Three products, one shared layer

Reactive · iMessage Flow Split Turns "dinner was $94.50, split 3 ways" into a payment request without leaving the chat.
Proactive · lock screen Flow Safe Forecasts what's safe to spend over the next 7, 14 and 30 days and nudges before a purchase.
Social · group chat Flow Together Group savings pots with scheduled contributions, milestones and opt-in accountability.

Shared layerProfilesBank and card APIsPredictionNotificationsSecurity

Handoffs between products

SafeSplitSafe warns that dinner will put you over budget. You go anyway, so Split offers: "Split this $85 to stay on track?"
TogetherSplitThe trip pot hits $2,000 but the booking is $2,340. Split offers to divide the $340 gap four ways.
SplitSafeYou and Sarah split costs eight times a month, so Flow suggests a shared expense pot instead.

Inside each product

Two Split Status screens side by side. Left: 2 of 3 paid, Devon's request not yet opened, with a prompt to send a gentle nudge. Right: Devon declined; a red banner says $31.50 is unsettled and no funds moved, with options to cover Devon's share, nudge again or cancel the split.

Designing for "no"

Most payment flows are drawn for the happy path. I spent as much time on what happens when a friend doesn't pay.

If someone hasn't opened the request, Flow doesn't nag them on its own. It asks the organizer whether to send a gentle nudge, because that's a social call, not a system one.

If someone declines, the screen says plainly that no money moved and offers three ways out: cover their share, nudge again or cancel. Nothing is left half finished.

Three Flow Safe screens. A lock-screen notification: Coffee puts you $12 over today's safe spend, with Skip it, I'm aware and Why am I seeing this. The Safe to spend screen: $27 today, a 7-day balance forecast that dips on rent day, and upcoming rent, bills and paycheck. The Why $27 today sheet: balance $1,482 minus rent, bills and a savings goal leaves $192 for 7 days, with confidence levels and buttons to correct a bill, paycheck date or account.

A heads-up that shows its math

Safe forecasts what's safe to spend from recurring bills, income timing and a savings goal, and speaks up only at a decision point, where the person already is: the lock screen, an iMessage thread or a widget.

Every number explains itself. "Why $27 today" walks through the math, says how sure Flow is about each part, and lets people fix a wrong bill or paycheck date on the spot.

Every nudge can be waved off, tuned or paused. When Flow learns from skipped nudges, it says what it changed and offers an undo.

Three Flow Together screens. Creating a pot: Cabo Spring Break, $2,000 by March 14, four members from the chat, $50 auto-added each Monday, and a switch to show what I've paid that is off by default. The group chat at 90 percent with a celebration for everyone and a private card only you see saying you're $40 behind, with ways to catch up. Releasing the pot: $2,000 to Sarah for the house, with Sarah and Marcus approved, your turn, and Alex not yet, since 3 of 4 must approve.

Saving as a group, without calling anyone out

Flow notices a group goal in the chat and offers a pot. Friends choose to join, then contribute on a schedule or with round-ups.

Celebrate in public, nudge in private. The group sees progress and milestones. Each person's amount stays private unless they share it, and "you're $40 behind" goes only to the person it's about.

Money moves only when the group agrees. Spending the pot needs 3 of 4 approvals, anyone can cancel, and requests expire in 48 hours.

Key decisions

Build into the chat, not a new app.The conversation is where the decision happens. The cost: Flow is limited by what each platform lets a third party show, so every card had to work in a small space.
Explain the number, then let people fix it.A forecast people can't question is one they stop trusting. Safe shows its math and confidence, and corrections update it right away.
Celebrate progress, don't shame.Together marks milestones and keeps each person's contribution opt-in, instead of calling out whoever is behind.
Show money status in words, not just color.Paid, pending, waiting, declined and failed each get a label and an icon, so status still reads for colorblind users and screen readers.

What exists and what doesn't. A 21-screen clickable prototype covering Split, Safe and Together, three earlier Figma prototypes, architecture docs and a case-study site. The message parsing and spending forecast are designed, not built, and I haven't tested the concept with users yet. If I took it further, I'd start by watching five friend groups settle a real shared bill.

Prototype: Split Prototype: Safe Prototype: Together Full case study Code