Decoupling a Live App with Domain Events
Part 2 of the IHA Migration Series: implementing a dual-write strategy and migrating core services to an event-driven architecture.
Robert Goniszewski
Senior Software Engineer & AWS Certified Solutions Architect
Summary
Senior Software Engineer and AWS Certified Solutions Architect (Professional) with 6 years of experience in Fintech and Event-Driven architectures. Expert in Node.js, TypeScript, and AWS Serverless technologies. Proven track record designing high-availability systems including credit scoring engines and AI-driven (RAG/LLM) content platforms. Skilled in Infrastructure as Code (Terraform/CDK) and monolith-to-microservices migration. In parallel, I maintain a private closed-source product built as a sole developer in stable support mode as an engineering lab for new ideas.
Methodology focuses on Domain-Driven Design, type-safety, observability, and cost-efficiency. Technical leadership emphasizes mentoring and the long-term ROI of architectural decisions, ensuring systems scale without technical debt accumulation.
Current focus: fintech systems and event-driven architecture, with active learning in AI/RAG/LLM integration and system design. Strategic areas: scalability, security hardening, AI infrastructure, and developer experience.
- OPEN SOURCE
Maintainer of Grimoire, a local-first bookmark manager with thousands of GitHub stars and hosted docs.
- SYSTEMS
Shipped production event-driven and serverless backends across fintech, lending compliance, and SaaS.
- WRITING
Publishes architecture migration notes and open-source retrospectives on goniszewski.com/blog.
OPEN SOURCE
CCTraygoniszewski/cctray
A macOS menu bar app for real-time monitoring of Claude API usage, cost, and burn rate.
SELECTED PUBLICATIONS
ALL ARTICLESFrom Next.js Monolith to Event-Driven Architecture: Why We Started and What We Built
Part 1 of the IHA Migration Series — documenting the move from a Next.js monolith to a distributed, event-driven architecture using RabbitMQ, and the three pain points that made it necessary.
It Happened Again - Building a Platform for Tracking Recurring Events
How I designed and built IHA - a platform for tracking recurring events through structured records and source-backed timelines.
EXPERIENCE
Mar 2026 — Present
Senior Full-Stack Developer — RBD (Rodzina Bez Długów)
Building and evolving an in-house CRM platform and adjacent internal tooling in the legal-tech domain. Owning architecture decisions across the stack while handling sensitive PII with appropriate data-protection and access controls. Delivery emphasizes AI-assisted development, iteration speed, and maintainable product architecture.
DOMAINLegal tech — in-house CRM solution and supporting internal tooling
RESPONSIBILITYArchitecture decisions and careful handling of PII-sensitive data flows
DELIVERY APPROACHAI-assisted full-stack development for rapid, high-quality iteration
Jun 2025 — Feb 2026
Senior Backend Engineer — Devopsbay
Modernizing existing code and implementing core decisioning logic for a US mortgage platform using TypeScript and Jest. Ensuring deterministic integer-based monetary calculations and compliance with strict lending regulations. Engineered a PoC for an internal AI-driven SEO automation module using LLMs.
DOMAINUS mortgage decisioning and lending-compliance backend modernization
KEY TECHNOLOGIESNode.js, TypeScript, PostgreSQL, Docker, Jest, DDD
Jan 2025 — Present (Part-Time)
Principal Architect & Sole Full Stack Developer — It Happened Again (IHA)
Designed and shipped a closed-source production SaaS end-to-end as sole developer. The platform is now in stable support mode, with focused after-hours iterations used to test modern architecture patterns and delivery approaches.
MODE & SCOPELTS / Stable with low maintenance workload; sole developer across architecture, backend, infra, and delivery
KEY TECHNOLOGIESNext.js 15, React 19, TypeScript 5, Node.js 22, PostgreSQL + Drizzle ORM, Better Auth, Redis + BullMQ, Meilisearch, Docker, Cloudflare
Jan 2024 — Jun 2025
Senior Node.js Developer — TSH (The Software House)
Developed and maintained serverless and microservice-based backend systems. Designed and implemented solutions with payment gateways, BaaS, and ML modules. Managed cloud infrastructure using Serverless Framework and Terraform. Led technical discussions, code reviews, and team support.
DELIVERY MODELServerless and microservice backend ownership with technical leadership and team support
KEY TECHNOLOGIESNode.js, TypeScript, Serverless Framework, Terraform, AWS (Lambda, DynamoDB, CloudWatch, Step Functions), PostgreSQL, GraphQL, Docker, REST API, CQRS, DDD
Jul 2022 — Dec 2023
Node.js Developer — NoA Ignite Poland
Salesforce Collection Solution: developed a serverless donation management system for a non-profit client using AWS Step Functions and CDK to automate complex payment flows. Digital Education Platform: designed and implemented a scalable backend with AWS Fargate, DocumentDB, and API Gateway. BITS Converter (global non-profit): advanced a publication converter, implementing MVP features and deployment pipelines using Node.js and AWS.
PROJECT MIXDonation automation, education platform backend, and converter MVP delivery for global non-profits
KEY TECHNOLOGIESNode.js, TypeScript, Python, AWS (Lambda, CDK, API Gateway, Step Functions, EC2, S3), Serverless Framework, Salesforce, IaC
Aug 2021 — Jun 2022
Full Stack Developer — Rspective (Client: BlueMovement)
Developed frontend (React.js, Next.js) and backend (Node.js/Nest.js, PostgreSQL) components for a subscription service. Integrated third-party services including Chargebee, Stripe, and Contentful. Built internal management dashboards.
PRODUCT SCOPEFull-stack subscription platform delivery with third-party billing and CMS integrations
KEY TECHNOLOGIESNode.js, Nest.js, Next.js, React.js, TypeScript, PostgreSQL, TypeORM, AWS, Stripe, Contentful
Feb 2021 — Aug 2021
Full Stack Developer — Michał Wrzosek sc: Centrum (Centrum Respo)
Developed a core API service from scratch using Node.js and Express.js. Extended an in-house WebSocket chat service and integrated MongoDB and Redis. Created an image processing microservice with AWS S3.
OWNERSHIPBuilt core API from scratch and expanded real-time chat plus media microservices
KEY TECHNOLOGIESNode.js, Express.js, JavaScript, MongoDB, Redis, AWS S3, WebSockets
Apr 2020 — Feb 2021
Junior Web Developer — 3mdeb
Contributed to web projects including a remote-controlled lighting system dashboard (Node.js/React) and a Zero Trust Security Platform PoC on AWS. Built early experience across Node.js, React, Python, and AWS.
EARLY FOCUSWeb platform implementation and AWS security PoC contributions across client projects
KEY TECHNOLOGIESNode.js, Express.js, Python, React, AWS (S3, IoT Core)
TECH STACK & EXPERTISE
TypeScriptExp: 5 y
JavaScriptExp: 6 y
PythonExp: 1 y
Node.jsExp: 6 y
NestJSExp: 2 y
Express.jsExp: 4 y
ReactExp: 4 y
Next.jsExp: 4 y
SvelteExp: 2 y
AWSExp: 4 y
TerraformExp: 2 y
DockerExp: 5 y
PostgreSQLExp: 5 y
MongoDBExp: 3 y
RedisExp: 3 y
GraphQLExp: 3 y
AI TOOLING
- Claude Code: Primary copilot for architectural decision-making and LLM-augmented UI/UX design exploration.
- Codex: Primary assistant for backend implementation, system design, debugging, and deep code reviews.
- GitHub Copilot: Multi-modal coding assistant used across day-to-day development tasks and rapid implementation workflows.
- Google Antigravity: Main AI-driven development IDE, powered by Gemini Pro.
CERTIFICATIONS & EDUCATION
2023
AWS Certified Solutions Architect (Professional)
Amazon Web Services
2022
AWS Certified Developer (Associate)
Amazon Web Services
2023
Graph Developer (Professional)
Apollo
2018 — 2022
Engineer in Software Engineering
WSB University in Gdansk
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