> who is mariusz rajczakowski? 01

Mariusz Rajczakowski

<ˈmar-yoosh rye-chah-ˈkov-skee> voice: ElevenLabs

Staff AI Engineer | Agentic Systems & LLM Applications | AI Product & Platform Architecture | Production AI at Scale

// United Kingdom

• AI Agents
• Large Language Models (LLM)
• Leadership

> experience 02

$ git log --career

1. Jul 2025 — PresentStaff Software EngineerVinny · London

   • Architected and implemented AI agent workflows for property-management maintenance that automate request intake, triage and vendor dispatch end to end, reducing human processing time by 95%.
   • Migrated production from a single AWS account to a governed multi-account setup with minimal downtime (centralised logging and alerting, zero-trust networking, policy-as-code in CI/CD), achieving ISO 27001:2022 and SOC 2 Type II.
   • Standardised the integration framework for third-party property systems; bespoke Entrata PMS and HubSpot CRM integrations were decisive in winning 2 major client contracts.

   Claude, OpenAI, OpenRouter, Vercel AI SDK, MCP, ElevenLabs, Pinecone, LangWatch, Cursor, Inngest, TypeScript, Next.js, React, Node.js, Postgres, AWS, Pulumi, Docker, GitHub Actions, Datadog, Vercel, Twilio, 360dialog, SendGrid

2. Apr 2025 — Jul 2026Fractional Technical Leadloanx.ai · Utah, US

   • Delivered a production AI title-analysis platform for real estate using multi-provider LLMs and 30+ durable workflows: ~35-minute median turnaround (~1–2 hours at p90) versus multi-day manual title work.
   • Architected a multi-source document AI pipeline across 4 record types, up to 350 documents per order with 50 parallel AI calls, so large orders run ~90% faster with no manual document triage.
   • Built LangGraph validation agents combining deterministic checks with LLM-as-judge scoring, routing ambiguous cases to structured manual review instead of hard failures.
   • Shipped an AI assistant with 12 tool-use functions over live title data (checklist, OCR, encumbrances, insurability).

   LangGraph, LangChain, LangSmith, Claude API, OpenAI API, Gemini API / Vertex AI, AI agents & tool use, LLM evaluation, Inngest, Python, PostgreSQL, React

3. Jan 2025 — Apr 2025Staff Software EngineerOmnea · London

   • Led discovery and delivery of the bank details project, streamlining financial operations and improving data accuracy.
   • Integrated third-party ERP systems (NetSuite, Microsoft Dynamics 365) and contributed to serverless AWS backend services (Lambda, DynamoDB).

   OpenAI, Cursor, AWS Lambda, API Gateway, DynamoDB, EventBridge, SQS, SST, Next.js, Node.js, React, PostgreSQL, Hasura, DocuSign, Sentry, Lumigo

4. Dec 2021 — Dec 2024Staff Software EngineerSourceful · London

   • Architected an integrated stock-management system replacing legacy spreadsheets and web apps; onboarded 10+ key clients and drove 55% of company revenue.
   • Led a greenfield microfrontend platform that became the default client offering, cutting deployment time by 90% and production integration issues by 95%.
   • Implemented cross-application passwordless authentication and SSO, reducing session interruptions by 95%.
   • Pioneered LLM-based proofs of concept extracting data from supplier quote documents, cutting product-brief matching from hours to minutes.
   • Raised engineering standards and mentored engineers; rebuilt the interview process (6 interviewers trained), lifting offer acceptance from 50% to 80%.

   OpenAI, TypeScript, Go, Python, React, Next.js, Node.js, Express, single-spa, Hasura, PostgreSQL, Redis, GCP, Pub/Sub, Kubernetes, Docker, Pulumi, GitHub Actions, Vercel, Auth0, Datadog, Sentry, Jest, DDD, microservices

5. Apr 2021 — Dec 2021Lead Software EngineerProximie · London

   • Led a 6-person engineering team that launched an AR surgical telepresence platform used in 13,000+ procedures across 500+ hospitals worldwide.
   • Built the HIPAA security layer: anonymised logging, role-based access control and full audit trails for surgical recordings.
   • Developed an Auth0-based user invitation system with robust session stability for extended procedures.
   • Cultivated a high-performing culture through structured agile practices and regular 1:1s.

   Auth0, AWS, CloudFormation, Terraform, Docker, ECS, GitHub Actions, Lambda, Node.js, PostgreSQL, Python, React, Redis, Serverless, SNS, SQS, TypeScript, video streaming, WebSockets

6. Sep 2019 — Apr 2021Senior Software Engineer / DevOps Engineer5App · London

   • Engineered LMS features (SCORM, signed-URL uploads, ClamAV scanning) that increased content compatibility by 90% for 5,000+ daily users across 10+ enterprise clients.
   • Implemented Terraform IaC, reducing environment setup from 2 days to 20 minutes and cutting deployment failures by 90%.
   • Built a Jenkins + Terraform CI/CD pipeline with ephemeral feature environments, reducing production incidents by 80%.

   AWS, CloudFormation, Docker, Docker Swarm, Express, Jenkins, Jest, Lambda@Edge, MySQL, Node.js, React, Redis, Serverless, Terraform, video streaming

7. Jun 2018 — Sep 2019Senior JavaScript EngineerNationwide Building Society · Swindon

   • Engineered an over-55s mortgage product that cut processing from 3 weeks to 5 days and handled 3× more applications, recognised by the Financial Times.
   • Developed a Storybook + InVision prototyping system that shortened feedback loops by 70% and reduced UI defects by 90%.
   • Built the NBS-UI component library used across 4 product teams with AA WCAG compliance.

   .NET, Kafka, event-driven architecture, JavaScript / TypeScript, Jest, microservices, Node.js, React, Semantic UI, Storybook, Grafana

8. Jan 2017 — Jun 2018Software EngineerHT2 Labs (acquired by Learning Pool) · Oxford

   • Developed Curatr features that increased user engagement by 50% and reduced certification completion time by 35%.
   • Built Elasticsearch full-text search for RedPanda, cutting average search time from 3.5s to 0.7s across 10,000+ daily queries.
   • Engineered a GDPR compliance tool for 10+ EU clients, reducing manual privacy request processing by 90%.

   AWS, Docker, Elasticsearch, GitHub Actions, JavaScript / TypeScript, MongoDB, MySQL, Node.js, React, Redis, xAPI

9. Nov 2015 — Jan 2017Software DeveloperSpace & Time Media · Reigate

   • Rebuilt the RefreshedDirect data broker platform; a multi-threaded Java CLI cut 16GB Experian CSV ingestion from 8 hours to 2 hours.
   • Engineered a Facebook Ad Booking Platform that cut campaign setup time by 60% and booking errors from 15% to under 1%.

   Angular, Vue.js, CircleCI, Java, JavaScript, Node.js, PHP, Laravel, MySQL

> education, certifications & languages 03

> contact 04