Ersel Seyit— Backend & Distributed Systems Engineer
Based in Brussels, Belgium, building and operating systems end to end — the infrastructure underneath, the services on top, and the interface users see.
Available immediately · on-site in Belgium and the Netherlands · remote worldwide, any timezone · EU citizen, no sponsorship needed
What I can take off your plate
Backend/Cloud
Spring Boot APIs, Kubernetes deployments, CI/CD automation, Keycloak OAuth2, parallel ML training pipelines.
Frontend
Flutter cross-platform apps, React dashboards with WebSocket streaming, real-time monitoring across 100+ metric types.
AI/ML
Medical imaging with TensorFlow at 93.7% accuracy, OpenCV fraud detection, GPT-powered natural language analysis.
- model accuracy
- 93.7%
- tests
- 605
- pods running
- 19
Experience
Software Engineer, Independent
Own products, not client work · Istanbul, Turkey · Sep 2025 - Present
- Self-directed: building and operating my own products rather than client work — the Base Station O&M platform (10 services, 19 K8s pods, 605 tests, still run alone) and Feather, a complete subscription app in Flutter (37K lines of Dart, 529 tests)
- Swapped the platform's Haversine maths for PostGIS spatial indexing: geographic queries over 100,000 records went from 8.5 s to 5 ms
- Shipped and still operate İstanbul Chess on Cloudflare Workers, and implement from primary sources: Raft consensus in Rust from the original paper, a lock-free C++20 library, and the Eraser lockset race detector in C++
Research Engineer
UpcoMinds · Brussels, Belgium · Feb 2025 - Aug 2025
- Deployed Java/Spring Boot services on a self-managed Kubernetes cluster on AWS EC2 with Amazon RDS (PostgreSQL), owning containerized rollout, ingress, and service-to-service connectivity for a production AI/ML pipeline
- Provisioned cluster resources in code through the Fabric8 Java client, and cut AI model training time by 70% by partitioning datasets into 10 segments for concurrent processing across EC2-backed nodes
- Wrote the Bitbucket Pipelines CI delivery pipeline, cutting deployment time by 60%, and secured API endpoints with Keycloak OAuth2 authentication and RBAC
Software Engineer, Freelance
Istanbul, Turkey (Remote) · Apr 2024 - Dec 2024
- Built a cross-platform medical imaging application in Flutter with custom TensorFlow models behind a REST API: four architectures compared, 93.7% accuracy and 95.4% F1 on a held-out test set
- Developed and delivered financial planning application with Python backend, integrating OpenAI GPT API for natural language budget analysis and personalized recommendations
Software Developer (intern → part-time)
Amani AI · Istanbul, Turkey · Jul 2022 - Feb 2023
- Shipped an OpenCV pipeline detecting invalidated Turkish identity documents in 2 weeks against a 2-month estimate, removing manual review from the fraud-check workflow
Skills
- Languages: Java, Python, Go, C, C++, Rust, TypeScript, Dart, SQL
- Backend: Spring Boot, Spring Cloud, Microservices, REST API Design
- Frontend & Mobile: React 18, Next.js, Astro, Flutter, Cloudflare Workers
- Cloud & DevOps: AWS (EC2, RDS), Kubernetes, Docker, CI/CD (Bitbucket Pipelines, GitHub Actions)
- Databases: PostgreSQL, PostGIS, MySQL, MongoDB, Redis
- Messaging: RabbitMQ
- Monitoring: Prometheus, Grafana, Zipkin, Loki
- Security: Keycloak, OAuth2, JWT, RBAC
- Tools: Git, Linux, Maven, TensorFlow
- Testing: JUnit, Mockito, Integration Testing
Education
- B.Sc. Computer EngineeringYeditepe University, Istanbul · 2020 - 2024
- Computer ProgrammingEge University, Izmir · 2018 - 2020
Availability
Available immediately — on-site in Belgium and the Netherlands, or remote for a team anywhere in the world, US and APAC hours included. EU citizen with the full right to work across the EU and EEA, so no sponsorship is required. Open to contract or permanent. Use the contact form or email erselseyit@gmail.com.
The story, in writing
Featured work
- İstanbul Chess
Live real-time multiplayer chess on Cloudflare Workers: one Durable Object per game for state isolation, WebSocket fan-out, server-authoritative clocks, and storage-backed reconnect. Ottoman vs Byzantine, playable now.
Live in productiontypescriptcloudflare-workersdurable-objects - Base Station O&M Platform
Solo-built telecom operations platform powering real-time base station monitoring and diagnostics.
8.5 s → 5 ms geo query, 100K recordsjavaspring-bootkubernetes - Feather — Quit-Smoking App
Complete subscription mobile product built solo in Flutter: custom design system, guided craving-support flow, scheduled notifications, in-app subscriptions, and privacy-first analytics.
2 platforms shipped (Android, web)flutterdartgo-router - Raft Task Queue
Distributed task queue built in Rust, with Raft consensus implemented from the original paper: leader election, log replication, an Axum REST API, and a real-time web dashboard.
0 tasks lost on node failurerustraftdistributed-systems - Concurrent Data Structures
High-performance C++20 concurrency library: a lock-free wait-free queue, a fine-grained concurrent hash map, and a work-stealing thread pool - plus the Eraser lockset algorithm for dynamic data race detection.
< 1 µs operation latencyc++lock-freeconcurrency - Transparent Proxy
HTTP/HTTPS proxy server with token-based authentication, content filtering, caching, and rate limiting. Built with Java 17 and JavaFX.
4 concerns, one pipelinejavaproxynetworking - X-ray Pneumonia Detection
Flutter mobile app for chest X-ray pneumonia detection using deep learning. Supports VGG16, EfficientNet, InceptionV3, and ResNet50 with on-device TFLite inference.
93.7% best accuracyflutterdeep-learningtensorflow-lite