CV

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Lisimba Gilkes

Experienced engineer helping founders and businesses design, build, and scale production-grade web, mobile, and AI systems.

CONTENTS

CONTACT

London, UK
📧 cv@lisimba.co.uk
🔗 linkedin.com/in/lisimbagilkes
🌐 lisimbagilkes.com

PROFESSIONAL SUMMARY

Experienced software engineer with 15+ years of experience across software engineering, data engineering, and technical leadership, delivering production systems across fintech, education, publishing, and consumer products.

Spent 8 years at Funding Circle (FTSE-listed fintech), progressing from engineer to engineering manager and scaling a data engineering team from 5 to 25 while improving delivery, systems, and engineering standards.

Proven track record of shipping 10+ products across web, mobile, APIs, and cloud infrastructure for both startups and established businesses.

Product-focused engineer with extensive experience working directly with founders and stakeholders to prioritise and deliver high-impact solutions aligned with business goals.

Recent work includes AI-integrated product development, building and launching production mobile applications using React Native, Firebase, LangChain, and LangGraph.

Open to senior IC, Tech Lead, or Principal Engineer roles combining hands-on engineering with ownership of architecture, product direction, and technical strategy.

TESTIMONIALS

As a non-technical founder, finding the right developer who was not only technically skilled but could also understand and refine my ideas was incredibly important. Working with Lisimba delivered exactly that and more. He helped roadmap my vision, enhance it, and ultimately bring PipLens to life.
— Founder, PipLens (Client)

I just want to thank you for all the hard work you put into the project. Especially you Lisimba — the magician behind it all. It was an absolute pleasure working with you.
— Dipesh, Cell Press (np2apps, Client)

Lisimba demonstrated deep technical and architectural expertise, consistently ensuring our data solutions met the highest standards of engineering excellence… He was always willing to lend a hand and was a dedicated mentor to new team members. I would gladly work with him again.
— Somnath Mahale, CTO, ProRhythmX Technologies (former colleague, Funding Circle)

TECHNICAL SKILLS

AI & LLM
AI workflow orchestration (LangChain, LangGraph), OpenAI API, prompt engineering, Cursor, GitHub Copilot

Languages & Frameworks
Ruby, Ruby on Rails (v3–v7), Python, JavaScript, TypeScript, React.js, React Native (Expo), Hotwire (Turbo, Stimulus)

Databases & Data
AWS (Glue), PostgreSQL, MySQL, ETL pipelines, Kafka, data modelling (relational, star schema), data warehousing

Cloud & Infrastructure
AWS (EC2, S3, RDS, CloudFront, ECS, VPC), Firebase, Terraform, Docker, Chef, CI/CD, Capistrano, Fastlane

Testing
RSpec, TDD, Playwright

Third-party Integrations
Stripe (Payments, Billing, Connect), PayPal, Twilio (Messaging), Auth0, Mux, Whereby, Algolia, Mailchimp

Leadership & Process
Engineering leadership, hiring & onboarding, mentoring, Agile, Scrum, Kanban, code reviews, pair programming, technical project management

WORK EXPERIENCE

Lead Engineer / Technical Partner (Freelance)

Independent / Various Clients
July 2011 – Present

10+ products shipped across fintech, media, publishing, education, and wellness.

  • Led full product delivery from concept, architecture, and wireframing through to launch and ongoing maintenance as the sole technical partner for non-technical founders
  • Delivered web applications, cross-platform mobile apps, RESTful JSON APIs, admin backends, and cloud infrastructure across the full stack
  • Built and upgraded Rails applications (v3 through v7) and cross-platform mobile apps using React Native and Firebase
  • Designed and implemented AI-powered product features using LangChain, LangGraph, and OpenAI
  • Advised clients on MVP scope, feature prioritisation, and monetisation strategy, enabling faster time-to-market and early revenue generation
  • Mentored junior developers and supported engineering hiring and onboarding for client teams

Career break (inc. AI R&D)

April 2024 – March 2026

Deliberate pause from full-time employment to explore AI coding tools and product development.

  • Designed, built, and launched Hey Celestia on Android; a production AI-powered mobile app with end-to-end encrypted conversations, deterministic astrology calculations, and a backend prompt management system decoupled from app store release cycles
  • Designed, built, and launched PipLens on iOS and Android; a social learning marketplace with 50+ early users, live webinars, video streaming, and Stripe Connect payments operational from day one
  • Developed production-grade expertise in LLM orchestration, AI workflow architecture, prompt engineering, and guardrail design using LangChain and LangGraph
  • Integrated modern AI coding tools (Cursor and GitHub Copilot) into day-to-day engineering workflows

Data Engineering Manager

Funding Circle UK
Nov 2020 – Apr 2024

  • Scaled the remote data engineering team from 5 to over 25 engineers, increasing delivery capacity and enabling parallel execution of key data initiatives
  • Mentored engineers across the team, including a TechWomen100 Award winner
  • Reduced time to compile DORA metrics reports from multiple days to minutes by developing an internal reporting tool in Rails and React
  • Improved engineering quality by overhauling post-mortem processes and introducing a 30-60-90 day onboarding framework adopted as the team standard
  • Partnered with stakeholders to define team roadmaps and align engineering delivery with business objectives

Senior Data Engineer

Funding Circle UK
Sep 2018 – Nov 2020

  • Led the onboarding of a remote offshore team of 25 engineers onto the data platform, aligning them with engineering standards and delivery practices
  • Introduced software engineering practices to an early-stage data team, including testing, version control, and code review
  • Developed ETL pipelines to offload complex reporting workloads from production Rails applications, improving platform performance
  • Integrated Rails applications with Kafka for real-time data streaming and designed star schema models to improve data warehouse query performance
  • Deployed AWS data lake infrastructure using Terraform

Senior Software Engineer

Funding Circle UK
Apr 2016 – Sep 2018

  • Contributed to the CASS compliance project by developing an asset reconciliation system in Ruby on Rails, replacing a manual multi-day process with a daily automated run
  • Designed a data snapshot pipeline for daily transaction reconciliation across the lending platform
  • Worked with cross-functional product and engineering teams to deliver features safely to production

Software Engineer (Contract)

Funding Circle UK
Sep 2015 – Feb 2016

  • Reduced production bugs as part of the Production Operations team, stabilising the core Ruby application
  • Designed and implemented a modern monitoring and alerting system from scratch
  • Codified production infrastructure using Chef cookbooks (provisioning Elasticsearch, MongoDB, Graylog, HAProxy, and PostgreSQL) and mentored engineers on best practices
  • Delivered high-availability infrastructure with failover to Rackspace

Senior Rails Engineer (Contract)

RedSofa London
Aug 2015

  • Migrated a production Rails application from Heroku to AWS, including VPC setup, ELB configuration, PostgreSQL migration to RDS, and transfer of 100GB of assets across S3 accounts, saving hundreds of pounds in hosting costs per month

Senior Software Engineer (Contract)

StreamSafe Video
Jun 2015 – Aug 2015

  • Implemented features and resolved issues in a Rails and Marionette JS application, improving reliability through environment isolation, idempotent communication, and asynchronous processing

Senior Software Engineer (Contract)

np2apps
Feb 2014 – Apr 2015

  • Led development of a digital journal publication platform for a world-leading medical publisher
  • Reduced development and infrastructure costs by introducing hybrid cross-platform mobile apps and migrating from legacy hosting to AWS
  • Mentored junior developers and supported hiring

Software Engineer (Contract)

Onfido Background Checks
Oct 2013 – Dec 2013

  • Developed a custom background check flow integrating third-party APIs for postcode lookup and identity document verification

Earlier Roles (Contract)

Cell Press (RELX Group), RELX Group, SportsVJ
2010 – 2013

  • Delivered a POC cross-platform mobile app solution for academic publishing, including content transformation services and AWS infrastructure
  • Developed RESTful APIs, video processing systems, and custom FFMPEG pipelines for a sports analysis platform

SELECTED PROJECTS

Hey Celestia — AI-Powered Astrology & Wellness App

React Native (Expo), Firebase, LangChain, LangGraph, OpenAI, TypeScript, Python

Designed and built a production-ready AI-powered mobile app combining conversational AI, astrology-based personalisation, journaling, and mood tracking.

  • Architected end-to-end encryption for AI conversations with per-conversation keys held exclusively by the user, ensuring no plaintext data at rest
  • Designed a modular AI system using LangChain and LangGraph, separating reasoning, prompt construction, moderation, and response generation for maintainability and control
  • Combined deterministic astrology calculations (birth charts, transits, lunar phases) with generative AI to produce consistent, verifiable personalised outputs
  • Built a backend prompt management system enabling AI behaviour updates without requiring app store releases
  • Implemented cross-platform subscription monetisation via RevenueCat with full App Store and Google Play compliance
  • Launched on Android with production-ready AI infrastructure

PipLens — Social Learning Platform

React Native, Firebase, Stripe Connect, Algolia, Mux, Whereby

Engaged from concept through to launch as the sole technical partner, delivering a social learning platform connecting experts with learners through live sessions, webinars, and project feedback.

  • Defined MVP scope and roadmap with a non-technical founder, enabling rapid progression from idea to production
  • Built a cross-platform React Native application with a scalable, serverless Firebase backend
  • Integrated Mux for video streaming and Whereby for live sessions, enabling real-time learning experiences
  • Implemented Stripe Connect for automated payments and payouts with built-in compliance
  • Added real-time, typo-tolerant search (Algolia) and product analytics (PostHog) to support growth and iteration
  • Launched on App Store and Google Play with early users and fully operational monetisation

Party Ace — Event Ticketing Platform

Ruby on Rails, Stripe, Twilio, Terraform, AWS, Docker

Supported and maintained an event ticketing platform supporting high-volume ticket sales and operational workflows.

  • Led the upgrade of a large Rails application from v3 to v7, improving maintainability and long-term scalability
  • Designed and implemented Stripe instalment payments for high-value festival tickets, expanding purchasing accessibility
  • Built a point-of-sale system with Twilio SMS integration, enabling offline ticket sales and operational flexibility
  • Containerised the application and migrated infrastructure from DigitalOcean to AWS using Terraform, improving reliability and deployment consistency

Beautra — Hair & Beauty Booking Marketplace

Ruby on Rails, Stripe Connect, PostgreSQL, AWS

Developed a marketplace platform enabling service providers to manage bookings, payments, and customer interactions.

  • Built a full-featured booking platform with custom service listings and scheduling workflows
  • Integrated Stripe Connect to automate payments, payouts, and KYC compliance for marketplace transactions
  • Implemented full-text search using PostgreSQL (pg_search), improving discoverability of services

NewHeirs — Church Social Media Platform

Ruby on Rails, PostgreSQL, AWS

Designed and developed a community platform supporting content sharing, communication, and member management.

  • Built a social platform with authentication, role-based permissions, and feed visibility controls
  • Implemented follow systems, direct messaging, and invitation-based onboarding for community growth
  • Delivered event management and multimedia content sharing features (text, image, video)
  • Enabled structured community engagement for church organisations

Zaskia — Music Sharing Platform for Independent Artists

Ruby on Rails, PayPal, AWS, RESTful API

Developed a platform enabling independent artists to distribute music and monetise content through subscriptions.

  • Built a music sharing platform with a freemium subscription model powered by PayPal
  • Developed a custom processing pipeline for zip extraction and ID3 metadata handling
  • Implemented automated weekly top-10 compilation generation based on user analytics
  • Exposed a RESTful API to support integration with a companion mobile application

EDUCATION

BEng Software Engineering with Computer Science
University of Birmingham
2004 – 2008

  • Built early AJAX-based application recognised by lecturer

A Levels (Computing, Electronics, Physics)
Josiah Mason College
2002 – 2004

  • Identified security vulnerabilities in internal system

ADDITIONAL

Interests
Exploring new technologies, reading non-fiction, DJing, cooking and travelling.

References available upon request