Abdikadyr Ulan

Java Backend Developer

Developing and maintaining production backend services for a live business platform. Primary focus: Java 21, Spring Boot, Camunda BPM workflows, and PostgreSQL. — Designed and maintained REST APIs used in production, ensuring scalability and clean layered architecture (controller/service/repository) — Built BPMN workflows in Camunda: subprocess, multi-instance, branching, process variables — Implemented @Transactional logic, role-based access, soft delete, idempotent operations — Optimized PostgreSQL queries (pagination, indexing, native SQL), improving response time and reducing load on core endpoints — Developed scheduled background jobs for async data processing — Maintained Docker environments for the dev team — Mentored junior developers and conducted code reviews, improving code quality and onboarding speed — Additionally contributed to frontend features using Angular Stack: Java 21 · Spring Boot · Camunda BPM · PostgreSQL · Docker · REST API · Angular

Fullstack / Backend Developer

Delivered end-to-end web solutions: backend services, integrations, and production-ready websites for clients and full web solutions for clients independently. — Built REST APIs and database schemas from scratch — Integrated third-party APIs (Google Sheets, OpenAI, Telegram Bot), enabling automation and external system connectivity — Developed systems with caching and background processing — Delivered landing pages and company websites (design → layout → integrations) Stack: Java · Spring Boot · PostgreSQL · JavaScript · OpenAI API · Telegram Bot API

Pet Project: Analytics Web App

Built a full-featured analytical web application backend in Rust (Axum) + PostgreSQL to deepen understanding of system design and build high-performance backend services outside my primary stack. — REST API with CRUD/UPSERT, filtering, search, pagination — XLSX import/export — Domain / service / repository layer separation Stack: Rust · Axum · PostgreSQL

Desktop Application Developer

Side Project Built a fully autonomous photo booth desktop application from scratch with a friend over the course of a year. The product was deployed at real events in Kazakhstan. What it does: — Captures photos via webcam, applies filters and background removal (TensorFlow BodyPix) — Prints photos directly via native printer integration — Runs autonomously: auto power on/off scheduling, auto payment handling, license-based activation — Admin panel for configuring booth settings remotely Technical highlights: — Rust (Tauri) — core application logic, system-level operations (printer API via WinAPI/winapi crate), hardware input handling (rdev, device_query) — Axum — lightweight internal HTTP server for inter-process communication — RSA + SHA2 — license key generation and verification system — React + Konva + Fabric.js — canvas-based photo editor with filters and cropping — TensorFlow.js (BodyPix) — real-time background segmentation — Zustand — state management across complex booth workflow — jsPDF + tauri-plugin-printer — print pipeline from canvas to physical printer The app reached production and was used at live events. Development was halted due to accumulated technical debt — a lesson in the importance of early architectural decisions. Stack: Rust · Tauri · React · TypeScript · TensorFlow.js · WinAPI · Konva · Vite