--- title: Yannis Kolovos - Senior Backend Engineer description: Portfolio of Yannis Kolovos, showcasing expertise in software architecture, system design, and backend engineering. author: Yannis Kolovos url: https://msroot.me canonical: https://msroot.me html_version: https://msroot.me/ language: en updated: 2026-11-05 --- # Yannis Kolovos > Senior Backend Engineer at [VODA.ai](https://voda.ai). Designing and building secure, scalable systems. > Remote · Greece · USA / EMEA This is the plain Markdown version of [msroot.me](https://msroot.me), for AI agents and text readers. With 20+ years of hands-on experience building complex systems from the ground up, I transform complex business requirements into high-performance, real-world applications. As a strategic thinker and hacker at heart, I approach system design through the lens of the [Unix philosophy](https://en.wikipedia.org/wiki/Unix_philosophy): simplicity, efficiency, and elegance. **Highlights** - Founding Engineer at Advocate: the platform processed $1.5T in loan value - AITD Excellence Award 2017: Best Use of Technology for Learning - Projects featured in The Guardian, CNN and La Stampa ## Experience ### VODA.ai — Senior Backend Engineer Sep 2026 – now · Remote · ISO/IEC 27001:2022 Event-driven backend for AI decision-support software used by municipal water utilities. - Moved synchronous workloads to a parallel, event-driven architecture with AWS SQS, event source mappings and Lambda. - Built high-throughput microservices on PostgreSQL and MongoDB in TypeScript, working across a polyglot codebase with Python and Go, using AI-assisted development. - Added background workers, WebSockets and end-to-end distributed tracing. - Built tooling that runs the full cloud stack on localhost (Docker, AWS, SQS, Lambda). Stack: Python, Go, TypeScript, AWS Lambda, SQS, PostgreSQL, MongoDB ### Advocate Technologies — Lead Backend Engineer · Founding Engineer Sep 2020 – Jan 2024 · New York · Remote · ISO/IEC 27001:2022 · SOC 2 Type II First employee. Designed the core platform for insurance compliance, a complex and regulated domain. The platform processed $1.5T in loan value. - Designed and ran the core AWS infrastructure, with deployments on Docker. - Built the core GraphQL API (Node.js, Apollo Server, MongoDB) with ACLs and field-level permissions. - Led and mentored a team of 3 engineers, and interviewed and hired new engineers. - Built a queue system (BullMQ, Redis), Redis caching, a rule-driven dynamic fields engine and Stripe payments. Stack: Node.js, GraphQL, Apollo, MongoDB, Redis, AWS, Docker ### Primary Colors — Lead Backend Engineer Sep 2019 – Jun 2022 · New York · Remote Led backend work for client platforms in retail, tailoring and travel. - **Hair Cuttery:** −75% request time by moving the legacy REST API to GraphQL. Joined many external APIs into one endpoint with Apollo Federation. - **Hemster:** built a 50+ model domain (orders, invoicing, payments, alterations, shipping) and a dynamic pricing system. −15% code complexity with a reusable query filter. - **Dorsia** (AI travel platform): −80% Google Maps API cost through caching. Geospatial search with Elasticsearch, load balancing and auto scaling on AWS. Stack: Ruby on Rails, GraphQL, PostgreSQL, Elasticsearch, Redis, AWS ### Earlier - **Nimber:** moved core technology from outsourced to in-house, built the backend team, and built the Stripe marketplace (charges, refunds, user verification). - **Bosch · Loud & Clear:** Lead Developer, end to end, for the MVP of a social-media crisis simulator that trains teams to handle a crisis. - **Sensis · Netfira:** eCommerce and accounting integrations. Built Active Resource style gems with ORM, using TDD. - **Symantec:** built microsites for Symantec's Australasia & Pacific marketing campaigns. They got strong open and conversion rates, and other Symantec regions used them as examples. ## Recommendations > Yannis is one of the most talented software engineers I've ever worked with. His ability to tackle complex problems with simple, efficient solutions is unmatched. The quality of his code is always clean and a pleasure to read. His unique mix of technical leadership, business-oriented thinking, and experience makes him stand out. Beyond his technical expertise, Yannis is a thoughtful and collaborative teammate who elevates everyone around him. Any team would be fortunate to have him! — Andrew Kordampalos, Zapier, AI Growth > Yannis is a true coding maestro, and I've learned an immense amount from his innovative approach to crafting generic code. What truly sets Yannis apart is his exceptional ability to foresee and address edge cases, making our company's API not only robust but bug-free — a rare feat in my professional experience. His dedication to the team and fellow developers is commendable. His exceptional skills, dedication, and inspiring leadership make him an asset to any team. — Ram Sankhavaram, IKEA, Software Engineer > Yannis is an enthusiastic, well-travelled developer, with good attention to detail, and a well-rounded coding style. In the months he worked on my team, I found him to be open and collaborative, and was impressed by his rigorous commenting, refactoring, and sense of how things 'should' be done. He was never too bogged down in functionality to remember the important, little things, which is refreshing in programmers of his calibre. — Neil Pearson, Atlassian, Senior Software Engineer All 7 recommendations: [LinkedIn](https://www.linkedin.com/in/ioanniskolovos/details/recommendations/) ## Technologies - **Languages:** TypeScript, JavaScript, Node.js, Ruby, Bash - **Architecture:** Microservices, Event-driven, Domain-Driven Design, High Availability, Load Balancing, Auto Scaling, Circuit Breakers, Rate Limiting, Caching Strategies, API Design - **APIs & Integrations:** GraphQL, Apollo, REST, gRPC, Express, NestJS, Ruby on Rails, Stripe, Google Maps API, ArcGIS - **Data:** PostgreSQL, MySQL, MongoDB, Redis, Elasticsearch - **AWS:** AWS, AWS Lambda, Amazon EC2, Amazon S3, Amazon RDS - **Cloud & Infrastructure:** Docker, Serverless, Nginx, Cloudflare Workers, Heroku - **Queues & Messaging:** RabbitMQ, AWS SQS, Amazon MQ, BullMQ, Sidekiq - **Observability:** OpenTelemetry, Sentry, Grafana, Prometheus, CloudWatch - **AI:** Neo4j, Qdrant, Ollama, ElevenLabs, MCP (Model Context Protocol) - **Security:** Auth0, JWT, OAuth, RBAC, ACL - **Testing:** Jest, RSpec, TDD, Integration & E2E, Benchmarking - **CI/CD & IaC:** Git, GitHub Actions, CircleCI, Terraform, Ansible ## Articles - [Building a PDF Chat System with RAG: A Step-by-Step Implementation Guide](https://yannis-kolovos.medium.com/building-a-pdf-chat-system-with-rag-a-step-by-step-implementation-guide-f2221f3c9881): a practical guide to implementing Retrieval-Augmented Generation with local LLMs and vector search. - [JsonLogic + GraphQL Unsupported Query Keys](https://yannis-kolovos.medium.com/how-to-solve-jsonlogic-graphql-unsupported-query-keys-using-lodash-fb9aa7365a51): handling unsupported JSONLogic operators in GraphQL queries with json-logic-js-graphql and Lodash. - [Keep your codebase clean with Rails API and GraphQL Connection Helpers](https://yannis-kolovos.medium.com/keep-your-codebase-clean-with-rails-api-and-graphql-connection-helpers-42ee479fd1f9): reusable helpers for GraphQL connections in a Rails API (ordering, datetime filters, search, total counts). More: [yannis-kolovos.medium.com](https://yannis-kolovos.medium.com) ## Open Source - [docuGraphRAG.js](https://github.com/msroot/docuGraphRAG.js): document processing and RAG library that turns text into knowledge graphs, with user-driven entity extraction, Neo4j and OpenAI. - [docuRAG.js](https://github.com/msroot/docuRAG.js): JavaScript library for RAG-powered document question answering with Qdrant and local LLMs. - [stripe-ruby](https://github.com/stripe/stripe-ruby): Stripe's official Ruby library. Helped with Stripe Connect by adding `Stripe::CountrySpec` support, which tells platforms what each country requires for connected accounts ([commit](https://github.com/stripe/stripe-ruby/commit/f8532d225e20cb6ded2bd9a672a6d8a0479b80ba)). More: [github.com/msroot](https://github.com/msroot) ## Volunteering - **Hacker:** ElevenLabs x a16z Worldwide Hackathon. Built [Kip.AI](https://devpost.com/software/kip-ai), an AI chat agent using the Google Gemini API and the ElevenLabs voice API. - **Mentor:** StCatsHacks Hackathon, the first inter-school hackathon in Athens, Greece (St. Catherine's British School). - **Mentor:** Startup Hackathon Melbourne, for entrepreneurial IT and design students from universities in Victoria. - **Hacker:** RedKite Hack to Help, Melbourne (YBF Ventures). - **Hacker:** Startup Hackathon, Melbourne (Inspire9). - **Volunteer:** Melbourne Community Toy Library, new layout. ## Honors & Awards - **Best Use of Technology for Learning:** Australian Institute of Training and Development (Loud & Clear) - **Startup Hackathon, Melbourne:** Student Entrepreneurs inc. - **Verification and validation for online transactions:** university thesis, Public Institution Of Higher Education Western Greece - **Master the Mainframe:** RMIT University / IBM ## Education - **M.Sc Master of Computing, Software Engineering:** RMIT University - **B.Sc School Of Economics, Business Administration:** Public Institution Of Higher Education Western Greece - Thesis: "Verification and validation for online transactions", grade 10/10. Covers the transaction lifecycle, layers and protocols, from TLS/SSL and the TCP TLS handshake to end-to-end security, certificates and encryption. ## Favorite Books - Design Patterns: Elements of Reusable Object-Oriented Software - Thinking in Systems - The Pragmatic Programmer: Your Journey To Mastery - Hackers & Painters: Big Ideas from the Computer Age - Genesis: Artificial Intelligence, Hope, and the Human Spirit - Clean Architecture: A Craftsman's Guide to Software Structure and Design ## Beyond the Code Explorer · Gastronome · Gardener · Music Lover · Philomath · Dad Outside work, I explore mountain trails, tend my two gardens, cook with quality ingredients, and bake sourdough bread and croissants, often experimenting with fermentation. As a fan of [Epicurus](https://en.wikipedia.org/wiki/Epicurus), I keep a balanced, mindful life with yoga, mixing music and a good book, driven by a love for continuous learning. ## Contact - MCP server: [https://msroot-mcp.msroot.workers.dev/mcp](https://msroot-mcp.msroot.workers.dev/mcp) (connect it in Claude or any MCP client) - Email: [yannis.kolovos+website@gmail.com](mailto:yannis.kolovos+website@gmail.com) - GitHub: [github.com/msroot](https://github.com/msroot) - LinkedIn: [linkedin.com/in/ioanniskolovos](https://www.linkedin.com/in/ioanniskolovos) - X: [x.com/yannis_kolovos](https://x.com/yannis_kolovos) - Instagram: [instagram.com/yanniskolovos](https://www.instagram.com/yanniskolovos) - Medium: [yannis-kolovos.medium.com](https://yannis-kolovos.medium.com) - Blog: [johnkolovos.blogspot.com](https://johnkolovos.blogspot.com) - npm: [npmjs.com/~msroot](https://www.npmjs.com/~msroot) - RubyGems: [rubygems.org/profiles/yanniskolovos](https://rubygems.org/profiles/yanniskolovos)