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Available for staff / principal rolesLondon, United Kingdom

Hi, I’mJeffery Mao.

Staff Full Stack Engineer shipping Payments at scale — across PayPal, Stripe, MoonPay, Revolut and Meta.

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Years engineering
10+
Top fintechs shipped
5
NFTs / day capacity
100M+
Treasury uptime
99.99%
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About

Engineering at the seam between money and AI.

10+ years shipping payments, crypto and AI platforms at PayPal, Stripe, MoonPay, Revolut and Meta — turning distributed-systems problems into resilient, GDPR-compliant product experiences.

Staff Full Stack Engineer with 10+ years building high-scale fintech, payments, crypto, and SaaS platforms across PayPal, Stripe, Revolut, and MoonPay. Strong background in distributed systems, checkout optimization, risk/fraud workflows, cloud infrastructure, and React-based product experiences. Proven record of leading cross-functional delivery, mentoring engineers, and shipping GDPR-compliant systems that improve conversion, reliability, and operational efficiency.

Focus

  • Payments
  • Checkout & fraud
  • Crypto / Web3
  • Agentic AI
  • Distributed systems
  • Cloud infrastructure
  • GDPR / privacy
jeffery.m.tek@outlook.com+44 7700 146373LinkedInGitHub
Experience

A decade of building money rails.

From Meta's Dublin campus tools to PayPal's Fastlane and agentic AI — a timeline of high-stakes systems shipped end-to-end.

  • Mar 2024 — Present

    PayPal

    Staff Software Engineer· CL7

    Remote

    Leading Go + Python services across guest checkout, agentic AI travel concierge, and the PayPal Ads attribution platform.

    Fastlane Guest Checkout

    • Go identity-resolution at <50ms peak latency.
    • Python ML risk unlocking CVV-less checkout.
    • React + JS SDK on BigCommerce and Adobe Commerce.
    • GKE multi-zone autoscaling absorbing 10× surges.
    • GDPR delete pipelines preserving audit trails.
    • Go
    • Python
    • React
    • GKE
    • GCP
    • ML

    Agentic AI Travel Concierge

    • Go orchestrator for multi-turn LLM travel chat.
    • Python RAG itinerary generation on live data.
    • One-tap Fastlane payment inside the chat flow.
    • Mentored 4 engineers on prompts and LLM evals.
    • Go
    • Python
    • LLM
    • RAG
    • Sabre API

    PayPal Ads Attribution Platform

    • Go bidding/delivery at <15ms decision latency.
    • Python attribution 40% more accurate than cookies.
    • RAG personalising creative from merchant + purchase data.
    • Petabyte-scale BigQuery + Dataflow event pipeline.
    • GDPR consent syncing ad prefs across PayPal + Venmo.
    • Go
    • Python
    • BigQuery
    • Dataflow
    • RAG
    • GCP
  • Jan 2021 — Mar 2024

    MoonPay

    Senior Software Engineer

    London, United Kingdom

    Built MoonPay's fiat-to-crypto on-ramp core and the HyperMint enterprise NFT platform, scaling to 500+ wallets and 100M NFTs/day.

    Fiat-to-Crypto On-Ramp Core

    • Java + Go on Visa/Mastercard rails at 99% auth.
    • Node.js 3DS + fraud middleware cutting false declines.
    • Python AML/KYC: sanctions, PEP, txn monitoring.
    • React on-ramp widget on 500+ wallets and dApps.
    • GDPR consent with granular retention controls.
    • Java
    • Spring Boot
    • Go
    • Node.js
    • Python
    • React

    HyperMint Enterprise NFT Platform

    • Java + Go backend for ETH / Polygon / Solana minting.
    • Batch-minting engine pushing 100M NFTs/day.
    • Node.js metadata / IPFS / royalty APIs — Universal, Death Row.
    • React dashboard for live minting + royalties.
    • Java
    • Go
    • Node.js
    • React
    • Ethereum
    • Polygon
    • Solana
    • IPFS
  • Apr 2018 — Jan 2021

    Stripe

    Senior Software Engineer· L3

    London, United Kingdom

    Shipped Terminal fleet management, Stripe Capital underwriting, and the Treasury account ledger across Node.js, Python, C#, and AWS.

    Stripe Terminal Fleet Management

    • Node.js OTA firmware/config service on AWS IoT.
    • React device-health dashboard with live diagnostics.
    • C# EMV-certified E2E encryption + key rotation.
    • Scaled AWS infra to 50,000+ concurrent terminals.
    • GDPR minimisation — purged logs, never stored PAN.
    • Node.js
    • React
    • C#
    • AWS IoT
    • Lambda
    • EC2

    Stripe Capital Underwriting Platform

    • Node.js services for loans, rules, and disbursement.
    • Python pipelines lifting credit-risk accuracy by 25%.
    • React merchant dashboard for offers + repayments.
    • SageMaker underwriting — funded 10,000+ SMBs in year one.
    • Node.js
    • Python
    • React
    • SageMaker
    • AWS

    Stripe Treasury Account Ledger

    • ACID C# ledger handling thousands of transfers/sec.
    • Node.js BaaS API layer with idempotency-keyed endpoints.
    • Embedded React components for live treasury balances.
    • Aurora cross-region at 99.99% — 1M+ accounts in 6 months.
    • GDPR encryption + right-to-erasure without ledger drift.
    • C#
    • .NET Core
    • Node.js
    • React
    • Aurora
    • AWS
  • Apr 2016 — Apr 2018

    Revolut

    Software Engineer

    Zurich, Switzerland

    Delivered Revolut's cryptocurrency trading integration and the Business platform that scaled to 35,000+ SMEs.

    Cryptocurrency Trading Integration

    • Go fiat/crypto conversion across 16 currencies at <100ms.
    • Node.js reconciliation at 50,000 trades/hour.
    • Python pricing engine with outlier detection + VWAP.
    • React Native trading UI — 10× DAU in 3 months.
    • GDPR export + deletion APIs preserving regulated records.
    • Go
    • Node.js
    • Python
    • React Native

    Revolut Business Platform

    • React micro-frontend dashboard for expenses/payroll/invoicing.
    • Node.js + Go IBAN issuance, halving cross-border time.
    • GCP Pub/Sub + Dataflow for live notifications + accounting sync.
    • Public API + portal — 35,000+ SMEs, 5× YoY revenue.
    • React
    • Node.js
    • Go
    • GCP
    • Pub/Sub
    • Dataflow
  • Oct 2015 — Apr 2016

    Meta

    Software Engineer Intern

    Dublin, Ireland

    Built internal productivity tools for Meta's Dublin campus, including campus-wide Wayfinder kiosks and utilisation analytics.

    Internal Productivity Tools

    • React Wayfinder kiosks with sub-second campus search.
    • Node.js room-booking sync with HR + facilities in <2min.
    • Python pipelines turning PIR logs into utilisation heatmaps.
    • Front-end controls wired to LED room-availability hardware.
    • Calendar audit cut ghost meetings 20% campus-wide.
    • React
    • Node.js
    • Python
Education

Where it started.

BSc in Computer Science

Dublin City University

Dublin, Ireland

2011 — 2015
Projects

Side builds & open source.

Selected products built outside of company hours — clinical AI, content generation, and payroll infrastructure.

ZipClinical

Clinical AI and team-task platform — Next.js customer app, Express/MongoDB API, React admin portal — with categorised AI modules, medical-code extraction, ZipTasks for organisations, and Stripe-based subscriptions.

  • Next.js
  • Express
  • MongoDB
  • React
  • Stripe
  • AI
View on GitHub

Kavya

AI-powered content authoring assistant designed to transform ideas into compelling web content effortlessly.

  • React
  • Node.js
  • LLM
  • AI
View on GitHub

Payroll-Check

Java 17 / Spring Boot payroll management backend (REST API) handling companies, employees, pay runs, and U.S.-style tax calculations (federal, Social Security, Medicare, state) — similar in scope to Gusto.

  • Java 17
  • Spring Boot
  • REST
  • Postgres
View on GitHub

Clinical AI ChatBot

Specialised clinical AI chatbot powered by RAG (Retrieval Augmented Generation), surfacing evidence-based medical information for healthcare professionals.

  • Python
  • RAG
  • LLM
  • Vector DB
View on GitHub
Toolbox

Skills & stack.

Languages and frameworks I reach for — paired with the cloud, data, and observability tooling needed to ship them safely.

Languages

  • TypeScript
  • JavaScript
  • Go
  • Python
  • Java
  • C#

Frontend

  • React
  • React Native
  • Redux
  • GraphQL
  • REST
  • WebSocket
  • Storybook

Backend

  • Node.js
  • Go
  • Spring Boot
  • FastAPI
  • Flask
  • gRPC
  • Event-driven services

Cloud & DevOps

  • AWS
  • GCP
  • Kubernetes
  • Docker
  • Terraform
  • GitHub Actions
  • Jenkins

Data

  • PostgreSQL
  • MongoDB
  • Redis
  • Aurora
  • BigQuery
  • Dataflow
  • Pub/Sub

Observability & Quality

  • DataDog
  • Grafana
  • Prometheus
  • Sentry
  • Jest
  • Cypress
  • ESLint

Domains

  • Payments
  • Checkout
  • Fraud / Risk
  • Crypto / Web3
  • Ledgers
  • GDPR
  • AI / LLM Integration
Contact

Let’s build something that ships money or magic.

Open to staff / principal full-stack, payments, and AI-platform roles — in London or remote.

jeffery.m.tek@outlook.com
+44 7700 146373LinkedInGitHub