03 / Experience

Ten years of
shipping the whole thing.

Fullstack developer with 10 years of end-to-end product delivery — from FinTech banking interfaces at Citi to multi-property infrastructure at scale. Strong in React/Next.js, TypeScript, Node.js and AWS, comfortable owning the whole delivery: architecture, API design, CI/CD and production monitoring. Currently focused on production LLM systems — RAG pipelines with hybrid retrieval, evals and enterprise security (RLS, audit trails). Available for senior IC or tech-lead remote contracts.

github.com/kezzlock
[ 01 ]

Career

2016 — present

  1. 2025—

    May 2025 — Present

    Senior Fullstack Developer & Architect

    Self-employed — SaaS Products · Remote

    • Designed and launched Fightime.tv — a PPV streaming platform built on Rust (Axum), Next.js 16 and AWS (EC2, S3, CloudFront, RDS). Owned the full lifecycle: architecture, stream ingest, auth and payments.
    • Built VerifyStock.com — a financial analytics SaaS with subscription management, real-time data sync and multi-tenant data isolation.
    • Engineered a closed-beta AI SEO tool: FastAPI backend, LLM integration for content analysis, PostgreSQL + pgvector for semantic search and a structured JSON output pipeline.
    • Actively building open-source utilities in Rust focused on performance-critical network and data-processing use cases.
    Rust (Axum)Next.js 16TypeScriptFastAPIAWSSupabaseStripeRedisPostgreSQL

  2. 2024—25

    Mar 2024 — May 2025

    Fullstack Developer

    Natural Pharmaceuticals · Warsaw (Hybrid)

    • Owned technical infrastructure for 200+ web properties — led the migration to Cloudflare WAF + CDN, reducing DDoS exposure and improving global response times.
    • Developed custom server-side monitoring and alerting tools maintaining a 99.9% availability SLA across the property portfolio.
    • Implemented frontend features in React/TypeScript; ran code reviews and enforced coding standards across a team of developers.
    • Worked with an e-commerce stack (WooCommerce, WordPress) at production scale — performance tuning, plugin architecture and custom REST API integrations.
    ReactTypeScriptNext.jsNode.jsCloudflareWordPressWooCommerce

  3. 2022—24

    Feb 2022 — Jan 2024

    Fullstack Developer

    Foundation for Polish Science (Fundacja Polskiej Akademii Nauk) · Remote

    • Led backend architecture and development for educational platforms — Django REST Framework, PostgreSQL and Docker, deployed on AWS EC2 + RDS.
    • Designed and scaled backend infrastructure for an EU-funded platform serving thousands of concurrent users — optimised query performance and introduced caching layers.
    • Managed technical compliance for EU-funded projects: documentation, audit trails and GDPR-aligned data handling.
    • Translated complex stakeholder requirements into well-documented REST APIs consumed by both web and mobile clients.
    DjangoPythonPostgreSQLAWS (EC2, RDS, S3)DockerREST APIs

  4. 2018—21

    Jun 2018 — Jun 2021

    Frontend Developer

    Citi Bank — FinTech Division · Warsaw (Remote)

    • Delivered secure, high-compliance banking frontend interfaces for the UAE and Bahrain markets — HTML5, CSS3 and JavaScript under strict accessibility and security requirements.
    • Collaborated with globally distributed teams across multiple time zones inside heavily regulated FinTech environments (PCI-DSS awareness, input validation, XSS prevention).
    • Integrated with the Avoka transactional platform for digital banking form workflows.
    HTML5CSS3JavaScriptAvokaFinTech compliance tooling

  5. 2016—18

    Jan 2016 — May 2018

    Freelance Fullstack Developer

    Self-employed · Remote

    • Designed and built custom web solutions for clients across e-commerce, marketing and SaaS verticals — full ownership from requirements to deployment.
    ReactNode.jsNext.jsPythonAWSStripe
[ 02 ]

Education

  • Finance and Accounting

    Kozminski University · Warsaw

    2008 — 2011

  • Philosophy

    Katolicki Uniwersytet Lubelski · Lublin

    2006 — 2008
[ 03 ]

Languages

  • Polish

    Native

  • English

    Advanced (professional working proficiency)