Robert Simmons.

20+ years building consumer products GenAI  ·  Personalisation  ·  Platform Engineering
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01 — About

About Robert Simmons

Turning ambiguous ideas into working prototypes that help teams align and move fast.

I'm a Senior Software Engineer with 20+ years of experience building consumer products at scale — most recently focused on Python-led GenAI systems, retail personalisation, and production-scale experimentation at Amazon.

My strongest skill is moving quickly from concept to working prototype, making abstract ideas tangible before major engineering investment is committed. I led the end-to-end delivery of an LLM-powered personalisation system that serves 100M+ customers and generated 500M+ personalised experiences — from prototyping through to serving, caching and customer-facing rendering.

Earlier in my career I built and owned the Alexa iOS SDK as sole engineer for approximately four years, and served as an internal security certifier completing 38+ security reviews across engineering teams at Amazon.

I'm strongest in environments where pace, hands-on leadership and a startup mentality matter — building something new, scaling a platform, or proving a product concept that unlocks the next stage of investment.

02 — Skills

Core Capabilities

Core

Python GenAI Prototyping LLM Evaluation Retail Personalisation Backend Architecture Experimentation Distributed Systems Event-driven Pipelines Observability CI/CD

Languages & Platforms

TypeScript Swift Objective-C Java Kotlin React Native FastAPI

Cloud & Systems

AWS Lambda / Lambda@Edge SQS & SNS EventBridge S3 / EC2 / VPC Bedrock Batch Caching

Security & Engineering Quality

Threat Modelling Penetration Testing OWASP Secure SDLC Code Review Mentoring

03 — Experience

Where I've Worked

Senior Software Engineer

Amazon

Current Role

  • Led end-to-end delivery of LLM-powered homepage personalisation — spanning content generation, evaluation, trust gating, infrastructure, serving, caching and customer-facing rendering.
  • Delivered systems serving 100M+ customers and generating 500M+ personalised experiences in under 30 days — from concept to live experiment.
  • Built an event-driven daily regeneration pipeline with cost controls, prompt optimisation, model selection, evaluation loops and production-grade operational guardrails.
  • Designed quality controls including LLM-as-a-judge evaluation, Wilson confidence interval sampling, and trust & safety gating for a storefront-facing AI experience.
  • Led a team of 5 engineers on a high-visibility retail initiative — owned critical path and all architecture decisions.
  • Led iOS delivery for Rufus chat voice input, adding depth in customer-facing AI across platforms.

Software Engineer II

Amazon

Previous Role

  • Sole owner of the Alexa iOS SDK for approximately 4 years — architecting and delivering wake word support, HTTP/2 downchannel streaming, performance improvements and Amazon Music integration.
  • Served as an internal security certifier, completing 38+ security reviews and building RAG-based screening patterns that reduced review cycles from weeks to days.
  • Reviewed 3,800+ pull requests over tenure — consistently raising the bar for code quality, maintainability and safe change.
  • Mentored successors to take over SDK ownership cleanly and sustainably, investing in long-term team capability.

Engineering Career Across Multiple Roles

Microsoft

Earlier Career

  • Built consumer messaging features at GroupMe — web and application layers using Ruby on Rails, PostgreSQL and AngularJS. Implemented an internal beta testing framework for faster iteration and earlier feedback loops.
  • Contributed to desktop software delivery on Skype Desktop in a large-scale consumer communications environment.
  • Improved test strategy, automation and release quality across Skype — shaping engineering quality across multiple delivery teams.
  • Worked on software quality and test automation for large consumer platforms on MSN.
  • Began career in programme and product delivery across Microsoft teams — progressing from student intern to senior software engineer over a decade at the company.

04 — Projects

Selected Work

Personal Project  ·  Open Source

Retail Loyalty AI Shopping Assistant

An end-to-end AI shopping assistant demonstrating personalised retail experiences — customer profiling, KNN-based recommendations, and conversational commerce with basket management and order placement. Built to showcase startup-style prototyping: concept through to a working browser-based SPA with full test coverage. A direct expression of the kind of rapid, high-quality prototyping that defines how I approach new problems.

Python FastAPI Polars scikit-learn KNN Claude Haiku Tool-driven Chat Single-Page App
View on GitHub

Personal Project  ·  iOS App  ·  TestFlight Beta

ReefLog — Marine Reef Monitor

Built out of genuine need as a marine reef tank enthusiast who wanted to move beyond spreadsheets. A fully native iOS app for logging water parameters, scheduling dosing, tracking maintenance tasks and keeping a reef system optimal. Covers the full native stack — SwiftData persistence with app-group widget sharing, local notifications and optional Apple Reminders integration via EventKit, home screen widgets via WidgetKit, and Siri Shortcuts. Every layer built to iOS platform standards, from domain model through to UI.

SwiftUI SwiftData WidgetKit UNUserNotificationCenter EventKit AppIntents iOS 17+
Join TestFlight Beta

05 — Community

Leadership & Community

0

Interns coached & mentored

0

Engineers reached fortnightly

0

Pull requests reviewed

Coaching & Mentoring

Coached 8+ interns and currently mentoring 2 apprentices with direct technical guidance, career advice, and structured learning paths.

Lightning Talks

Runs a fortnightly lightning talk series for 50+ engineers — creating space to share solved problems, surface better practices and build cross-team connection.

Engineering Standards

Known for high standards in code quality, maintainability, testing discipline and safe change — demonstrated through 3,800+ pull requests reviewed over tenure.

Security Certifier

Served as an internal security certifier completing 38+ reviews, and built RAG-based screening tools that cut review cycles from weeks to days.

Volunteering

Mums in Technology

Instructor — Web Technologies & Programming Fundamentals

Earlier in career

Volunteered with this group of women over a 6-week programme, delivering hands-on training in web technologies and the fundamentals of programming. One of the most rewarding things I've done — seeing people find their confidence with code for the first time.

06 — Certifications

Credentials

Amazon

AWS Certified AI Practitioner

Issued 2026

Microsoft

Exam 70-562 — TS: .NET Framework 3.5, ASP.NET Application Development

Issued 2009

BCS

ISTQB-BCS Certified Tester Foundation Level

Issued 2011

07 — Connect

Let's Connect

Open to conversations about GenAI, personalisation, platform engineering, or roles where pace and hands-on technical leadership matter.

LinkedIn GitHub