Артем

Artem Demchyshyn TW8, London, UK
[open contact info](look above in the "contact info" section)
[open contact info](look above in the "contact info" section)
Java Software Engineer: Core Java, performance [open contact info](look above in the "contact info" section)
and automated testing github.com/DemchaAV

SUMMARY
Java software engineer with a Core Java focus (Java 17/21, concurrency, generics, Streams), building libraries, backend
applications and developer tools from API design to testing, releases and documentation. Created an open-source Java
document engine on Maven Central with 30 releases and re-architected it as a semantic document compiler into an
immutable, backend-neutral layout graph; in local benchmarks it rendered a 1,000-row report 4.3× faster than iText with
3.5× less heap. Automate verification wherever possible: layout snapshots and pixel-level visual diffs run in CI on GitHub
Actions and gate the routine additions made by AI coding agents. Previously led engineering planning, delivery and quality
control, and mentored 8 team members. Right to work in the UK.

SKILLS
Languages Java 17/21, SQL
Core Java Concurrency, generics, Streams, ServiceLoader/SPI
Testing and JUnit 5, Mockito, integration testing, snapshot testing, visual regression testing, Playwright
automation
Build and delivery Maven, Maven Central publishing, Git, GitHub Actions, CI/CD, Docker, Docker Compose
Backend and APIs Spring Boot, Spring MVC, Spring Security, REST APIs, JWT, Jakarta Bean Validation, MapStruct,
OpenAPI/Swagger, JSON Schema
Persistence Spring Data JPA, Hibernate, MySQL, Flyway, JDBC
AI integration Gemini, OpenAI and DeepSeek APIs, structured outputs, coding-agent workflows, Claude Code, Codex,
MCP server design

WORK EXPERIENCE
Independent Software Developer Apr 2024 – Present
Independent projects and open source, London, UK
• Build and maintain Java libraries, backend applications and developer tools end to end: API design, implementation, testing,
releases and documentation.

Bartender Aug 2022 – Present
Caprice Holdings – Scott's Richmond, London, UK
• Promoted within 7 months for consistent performance in a demanding hospitality environment.

Lead Engineer Sep 2016 – Feb 2022
Nikoplast, Odesa, Ukraine
• Mentored 8 team members and led engineering planning, delivery and quality control.

EDUCATION
Bachelor of Science in Hydraulic Engineering Sep 2012 – May 2017
Kherson State Agrarian and Economic University, Ukraine
UK equivalent: 2:1

Java and Spring Backend Development Dec 2023 – Present
Independent Study and Project Development
Practical study through backend applications and open-source library development.

CERTIFICATIONS
Spring Boot REST APIs: Spring Security, JWT & Role-Based Access — Code with Mosh Jul 2025
Spring Boot & Spring Data JPA: Hibernate, JPQL & Transactions — Code with Mosh May 2025
Oracle SQL: Querying & Managing Relational Databases — Udemy (Zaur Tregulov) Jan 2025
Advanced Java Core: Collections, Generics, Stream API & Multithreading — Udemy (Zaur Tregulov) Jun 2024

PROJECTS
GraphCompose Open source
Java 17/21, Apache PDFBox, Apache POI, Maven, JUnit 5, GitHub Actions
• Created and maintain an open-source Java document engine on Maven Central: 113 GitHub stars, 30 releases (current v2.4.0),
15,000+ artifact downloads across June–August 2026 and 6 organisations in ongoing use (Scarf, September 2026).
• Benchmarked performance locally against iText 9.7.1 and JasperReports 7.0.8 (median of 5 runs): the engine rendered a
1,000-row report 4.3× faster than iText and as fast as JasperReports, while allocating 3.5× less heap than iText and 2.7× less
than JasperReports.
• Redesigned the architecture as a semantic document compiler behind a declarative DSL: the document tree compiles through
registered node definitions into an immutable, backend-neutral layout graph, rendered by pluggable PDF, beta PPTX and partial
semantic DOCX backends.
• Hand-wrote the original engine in Java on an entity-component-system design, with its own layout, pagination and rendering
systems over Apache PDFBox, where atomic and breakable objects push each other across pages inside nested containers and
stacks.
• Automated verification instead of reading logs and PDFs by eye: layout snapshots store resolved geometry as JSON baselines
and pixel-level visual diffs catch colour and layering errors, so every template upgrade in CI shows exactly what moved.
• Grew the library to 58 reusable templates across six document families; once the core stabilised, AI coding agents took over
routine additions such as new shapes and render methods, gated by snapshots, visual diffs and binary compatibility checks.

CVRewriter Public architecture showcase; private source code
Java 21, Spring Boot 4, Spring Security, JPA/Hibernate, MySQL, Flyway, React, TypeScript, Docker
• Wrote the Spring Boot backend of a CV tailoring and application tracking platform: REST APIs, MySQL persistence, Flyway
migrations and GraphCompose PDF generation; the React frontend was built by AI agents to my specification.
• Integrated HTTP-first vacancy scraping with Playwright fallback, schema-validated output from three AI providers, and real-time
progress through Server-Sent Events (SSE).
• Implemented JWT authentication, job-scoped SSE tokens, AES-GCM encryption for sensitive fields, and Stripe subscriptions and
webhooks.
• Tested backend behaviour and security with JUnit and Mockito, and set up isolated development, test and production
configurations with Docker Compose.

GraphCompose AI Flow Open source
Node.js, TypeScript, Java, ImageMagick
• Designed the architecture of a coding-agent harness for Claude Code, Codex and Gemini CLI that turns document references into
reusable GraphCompose Java templates; the Node.js/TypeScript code is written by AI agents to my design.
• Designed a version-aware API knowledge base for GraphCompose, generated from its compiled classes: an agent that asks for a
paragraph gets only the matching slice of the API rather than whole classes, so it works from real signatures instead of guessing
methods that fail compilation.
• Defined the workflow and gates: revision management, layout diagnostics, visual verification and bounded iteration; current
version v0.23.0.

CV Rewriter MCP Private source code
Java 21, Spring Boot, MCP, GraphCompose, Docker
• Designed a local MCP server that lets AI assistants tailor a CV to a job advert without being able to change facts: the tool schema
has no field for employers, titles or dates, and every patch is validated against the profile before it is stored.
• Specified its safeguards and scope: 15 tools, checks for unsupported technologies, inflated ownership and copied lines,
SSRF-guarded job fetching and deterministic rendering to 13 CV templates; implemented with AI coding agents from my
architecture and plans.

LANGUAGES
English Fluent
Ukrainian Native
Russian Native