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Hi, I'm James. Principal Software Engineer.

I design and build resiliency systems for real-time payments, then experiment on the side with ML, analytics, and projects rooted in sport and motion.

Technology — Go • AWS • Observability Finance — Payments • Analytics Sport — Tennis • Motion • Hardware
$ cd ~/work $ ./contact
WORK

Dashboard of systems & side projects.

Use the filters to view projects through the lens of technology, finance, or sport.

Production System
Go AWS — ECS, Route 53 CloudWatch & New Relic

Resiliency Engine — Card Authorizations

Highly concurrent Go engine that auto-detects failures across multi-tenant ECS clusters and routes live traffic to healthy cells — protecting card authorization systems processing $780B.

  • Cut MTTR 95% to ~1 minute; protects $2M+ net income/yr.
  • Zero Sev-3+ incidents across 12+ shielded services over the past year.
  • Platform spans 8 tenant apps, 15+ teams, 3 orgs — built as sole lead engineer.
  • Strict cross-region consistency via DynamoDB MRSC, conditional writes, and a custom peer-to-peer lease protocol.
Platform & SRE

Kubernetes Platform — Mission-Critical Payments

Management and ownership of Kubernetes infrastructure for Capital One’s mission-critical payment processing systems, including cluster operations, reliability, and deployment workflows across multiple environments.

Kubernetes Terraform Jenkins ArgoCD Splunk · New Relic · OTEL AWS
Phux terminal control plane demo
Agent Infrastructure

Phux — Terminal Control Plane

Share real terminals with your agents: terminals as addressable objects on the wire, so humans, GUIs, and AI agents observe and control the same live session from identical byte streams.

libghostty Wire protocol WebAssembly WSS / QUIC MCP
Failover demo: primary provider killed mid-traffic, requests shift to backup with zero client errors
AI Infrastructure

LLM Resiliency Router — Go

Reverse proxy that keeps LLM traffic flowing through provider outages — health cells with ejection and half-open probes, priority failover mid-stream, zero client-visible errors. The card-payments resiliency pattern, applied to AI serving.

Go OpenAI-compatible Failover Health cells Chaos harness
Live DORA metrics → The writeup →
RL tennis demo: a paddle agent slides, swings, and returns serves over the net
Reinforcement Learning

Brax Tennis RL — JAX

A PPO agent taught to play tennis in Google's JAX physics engine: 95% interception, 72% returns over the net, and self-play rallies that lengthen every generation. The collegiate tennis player taught an agent to play — reward hacks and all.

JAX Brax / MJX PPO Self-play D1 tennis
The three-part writeup →
Court Finder demo: locating nearby public tennis courts in NYC, searching Central Park, and opening a facility's details
Web App

Court Finder — All About Tennis

Mobile-first map of public tennis courts across all 50 states + DC: clustered markers, distance-aware "near me" search, surface and lighting filters, and per-facility detail with directions. Data pulled offline from OpenStreetMap and NYC Parks and served as static JSON.

React TypeScript Leaflet OpenStreetMap GitHub Pages
Find a court →
Resy Snipe Bot demo preview
Automation

Resy Snipe Bot — NYC Reservations

Personal Go-based bot that monitors Resy availability and automatically snipes hard-to-get restaurant reservations in New York City when slots open.

Go HTTP / APIs Scheduling Automation Watch demo gif ↗
Tesla CNN project
ML / Computer Vision

Tesla CNN — Keras/TensorFlow

Custom convolutional neural network on a curated Tesla dataset with augmentation and careful tuning.

Python Keras TensorFlow
Simulation
Python PyTorch PyGame

Self-Driving Car Simulation — PyTorch

Simulation using Python, PyTorch & PyGame to explore navigation, decision-making, and control logic in a constrained environment. A playground for thinking about stability and feedback.

Watch demo video ↗
CI/CD & Validation

Qualcomm — Hardware Validation Pipelines

Validated 5G/4G/3G modem subsystems on an FPGA farm — 3 timing & power bugs caught pre-tape-out, 7 production SoCs shipped, and triage time cut 90% via automation and visualization pipelines.

Python Trace32 Jenkins Splunk Cron Emulation platform
Tello Drone senior project
Computer Vision

Tello Drone — YOLO & OpenCV

DJI Tello controlled via Python APIs, with YOLO & OpenCV for face tracking and motion-aware control.

Python OpenCV YOLO
All About Tennis website
Ecommerce & Brand

All About Tennis — Scottsdale

Modern web presence, media, and merchandising for a family-owned tennis & pickleball shop.

Shopify Analytics Tennis
NFT & Creative Coding

Phantom Barons — Cardano NFT Collection

Personal project generating a randomized NFT collection on the Cardano network, with a Python art pipeline and a React front end, storing assets and metadata via IPFS.

Python React Cardano IPFS Generative art
PoseNet demo
Motion & Web ML

PoseNet — TensorFlow.js

In-browser pose estimation to track human motion in real time via TensorFlow.js.

JavaScript TensorFlow.js
Apple vs Microsoft financial workbook
Finance & Analytics

Apple vs Microsoft — Financial Workbook

Comparative workbook analyzing key performance indicators and long-term trends for two major tech giants.

Excel modeling Fundamentals
Knapp Scholars webpage
Storytelling

MIT x USD — Knapp Scholars

Feature page for a computational origami collaboration, blending math, art, and narrative to showcase research.

Content Design
Audio & Hardware

Music Visualizer — Arduino & LED Strips

Side project using Arduino, acoustic sensors, and programmable LED strips to transform music into real-time light patterns — effectively turning a room into a live visualizer.

Arduino C / C++ Acoustic sensors LED strips Real-time visuals
TECH FINANCE SPORT
ABOUT

Systems thinker with a sports engine.

I'm a systems-minded engineer with a background in competitive tennis and a dual focus on Computer Science and Finance. That mix shapes how I think about risk, reliability, and the stories data can tell.

I care about architectures that stay composed under load: multi-AZ routing, health evaluation, observability, and controlled failure modes. I also enjoy projects that connect code to the physical world—whether that's motion, audio, sport, or people using a product in real time.

FOCUS

Resiliency, SRE, and real-time systems for payments and financial flows.

STACK

Go, Python, AWS (ECS, Route 53, DynamoDB, CloudWatch), New Relic, Docker, Kubernetes, GitHub Actions.

Portrait of James Ponwith
NYC • London. Outside work, you'll usually find me on a tennis court, planning the next trip, or tinkering with side projects that mix tech, sport, and storytelling.
CONTACT

Let’s build something resilient.

Open to new roles, collaborations, and conversations around resiliency engineering, payment systems, analytics, and creative technical projects in tech, finance, and sport.

Email me
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