FinTech Consulting & Payment Systems

MysDeFi

Before you build it, prove it.

A boutique fintech studio. Validate your technically risky payment idea with a working prototype — before committing to full-scale development. Discovery through demo, typically in 2–6 weeks.

Ming-Li Liu, Principal  ·  25+ Years in Payments
Discuss a PoC
hello@mysdefi.com Principal bio → San Francisco Bay Area
Why Clients Hire Us
  • Prototype instead of PowerPoint
  • Principal-led, end to end — no handoffs
  • Deep payments expertise
  • Working demo in 2–6 weeks
  • Clear go / no-go recommendation
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You Should Talk to Us If

✓You are a fintech company validating a new payment product or idea
✓You are investigating AI-driven checkouts or agentic commerce
✓Your engineering team is not sure the idea is feasible
✓You are exploring BLE/UWB as alternatives to NFC
✓You need a demo for investors, executives, or conferences
✓You are evaluating crypto settlement, on-ramps, or off-ramps

We do not build production payment systems first. We build the prototype that tells you whether you should.

How We Engage

Discovery & Feasibility Sprint
A short, focused sprint to pressure-test the idea — scope the real technical risk, define what "done" looks like, and confirm the PoC will answer the actual business question.
→
Prototype
Hands-on build of the working prototype — full stack, no handoffs — targeting the riskiest technical assumptions first so blockers surface early, not at the end.
→
Demo & Technical Recommendation
A working demo plus a clear, business-ready recommendation on feasibility, risk, and what it takes to go from prototype to production.

What We Do

What We Bring
  • Feasibility in hours, not weeks 25+ years of payments standards — EMV, GlobalPlatform, ISO 7816, NFC, ISO 14443 — mean we can identify where the hard parts are before a line of code is written, and scope a PoC that actually answers the business question.
  • Proven PoC track record Proof-of-concept demos presented at industry conferences and prototypes to show decision makers. The job: make a business hypothesis tangible enough to get a decision.
  • Full stack, no handoffs From embedded firmware and NFC chip specs to cloud APIs and cross-platform mobile UIs — the entire prototype stays in one set of hands, which means faster iteration and no translation loss between teams.
  • Business ↔ engineering bridge Backed by CTO (Zenius Solutions) and Director of Engineering (SimplyTapp) experience — we speak both languages, translating a business hypothesis into an architecture decision and back again.
Problem areas we are targeting
  • Crypto Rails for Loyalty & Micropayments Traditional card rails have an economic floor — sub-cent transactions are not viable. Stellar and similar networks remove that floor entirely. If your business model depends on rewarding users at scale — loyalty points, content tips, engagement incentives — there is now a practical, production-ready technical path.
  • Agentic Commerce & AI-Driven Checkout AI agents that understand a customer's wallet, rewards balances, and purchase context can route them to the payment method that benefits them most. This is a competitive differentiator for any issuer, wallet, or merchant platform — and the agent infrastructure to build it now exists and is deployable.
  • Proximity Payments via BLE, WiFi Aware & UWB NFC is a 20-year-old, centimeter-range standard. BLE, WiFi Aware, and UWB offer longer range, richer spatial context, and new interaction models. Applying these to in-person payments opens use cases NFC cannot reach — paying from across a restaurant, contactless drive-thru, or high-precision proximity verification for high-value transactions.

Recent Work

C Orchestrator Discovery Payment Checkout
Agentic Commerce
AI-Powered Shopping Assistant
Can an AI agent choose the customer's optimal payment method?
Prototype A multi-agent shopping platform built on Google ADK and the Universal Commerce Protocol. An orchestrator agent delegates to specialist sub-agents for product discovery, payment instrument selection, and checkout — steering the customer toward the payment method that maximizes their rewards.
Solved Reliable orchestrator→specialist agent handoffs; multiple payment integrations unified behind one conversational flow; parity between React/TS web and iOS SwiftUI with voice input; serverless deploy to GCP.
ResultYes — a complete discovery-to-checkout flow driven entirely by conversation, decision-ready for evaluating agentic commerce as a rewards-routing differentiator.
Google ADK LiteLLM Python FastMCP UCP Stripe Shopify React SwiftUI Firestore GCP
BLE / UWB
Wireless Payments
Proximity Pay
Can BLE/UWB replace NFC at the point of sale?
Prototype Customers pay from their seat or car using Venmo or Cash App — no card handoff, no terminal to pass around. The merchant's iPhone discovers nearby customer phones wirelessly over Bluetooth and UWB, then initiates the payment request without any physical contact.
Solved Device discovery and ranging over BLE + UWB (NearbyInteraction / MultipeerConnectivity); three processors with different SDK models (PayPal/Venmo, Square/Cash App, Stripe/Apple Pay) unified in one flow; contactless payment with no card handoff or dedicated terminal.
ResultYes — a merchant iPhone can replace dedicated POS hardware and initiate payment without physical contact, validating BLE/UWB as a viable NFC alternative.
Swift BLE UWB NearbyInteraction MultipeerConnectivity Firebase Stripe Terminal PayPal SDK Venmo SDK Cash App Pay SDK
XLM 1000s of sub-accounts
Crypto Micropayments
StellarBack
Can crypto rails make sub-cent micropayments economical?
Prototype A rewards platform on the Stellar network that makes micropayments practical at scale. Senders tip creators using a simple @handle syntax — no wallet setup for recipients. Muxed accounts fan out to thousands of virtual sub-accounts from a single on-chain address, keeping fees negligible even at high volume.
Solved Sub-cent economics via muxed accounts fanning out to thousands of virtual sub-accounts from one on-chain address (fees stay negligible); recipient onboarding with no wallet setup (@handle syntax); multi-asset (XLM + USDC) via path payments.
ResultYes — a $0.0001 USDC minimum transfer, economically impossible on card rails, proving crypto viable for at-scale micropayment rewards.
Stellar SDK Firebase USDC XLM Muxed Accounts Path Payments Make.com TypeScript React

Core Capabilities

💳
Payments & FinTech
Standards-level fluency across card, mobile, and crypto rails — from acquiring and risk logic to DeFi settlement.
EMV GlobalPlatform ISO 7816 Contactless / NFC / ISO 14443 ISO 8583 Mobile / P2P Payments Stellar / DeFi / Payments
⚡
Full-Stack Engineering
Backend to native mobile in one set of hands — built to move a prototype fast without cross-team handoffs.
Python / FastAPI / FastMCP React / Node.js / TypeScript Java / Spring Boot iOS (Swift) Android Flutter
🗄️
Cloud & Data Infrastructure
Production-grade deployment and data pipelines for prototypes that need to hold up under real usage.
GCP / Firebase AWS Docker LiteLLM MySQL / MongoDB CI/CD
🔐
Hardware & Security
Deep embedded and cryptographic expertise — where most fintech PoCs actually run into trouble.
Cryptography / HSM Tokenization Smart Cards / JavaCard Embedded Firmware