Yusuf Koşar
Full Stack Developer
Full-stack developer building production-grade web applications
Who Am I?
A full-stack developer studying Computer Science at the University of the People and a graduate of the Workintech Full-Stack program. I build production-grade applications with React, TypeScript, Node.js and PostgreSQL.
I care about clean architecture, testability and user experience. From idea to production, I build end-to-end products with CI/CD, type safety and scalable data models.
Featured technologies
- React
- Next.js
- TypeScript
- Node.js
- PostgreSQL
- Prisma
My Tech Stack
The tools I use end to end — from frontend to database, testing and deployment.
Frontend
- React
- Next.js
- TypeScript
- JavaScript
- Tailwind CSS
- Framer Motion
- Redux
Backend
- Node.js
- Express
- Prisma
- REST API
- JWT
- OAuth
Database
- PostgreSQL
- Supabase
- Convex
Tools
- Git
- Docker
- GitHub Actions
- Vitest
- Playwright
- Cypress
Selected Work
Applications shipped to production, tested, and solving real user scenarios.
Stacklight
Error Tracking & Grouping Platform
The read path is decoupled from the write path: the dashboard talks to the database directly, so it keeps working even while the ingestion service is asleep. Errors are grouped by deterministic fingerprinting, with versioned Java and JS stack trace normalization. Three anomaly detectors were compared in shadow mode, and the active detector was swapped based on the measurements. 320 tests, six CI workflows.
- Java
- Spring Boot
- Next.js
- TypeScript
- PostgreSQL
LocalMediaKit
Media Kit Platform for Content Creators
Published pages are served from the edge as immutable snapshots, so a shared link opens instantly even while the backend is asleep. A timing oracle on the password reset endpoint was closed by moving delivery to an outbox, giving a constant response time verified by measurement. 330 backend + 105 frontend + 13 E2E tests; ArchUnit architecture rules fail the build on violation, PIT mutation score 97%.
- Java
- Spring Boot
- Next.js
- TypeScript
- PostgreSQL
Pulse
Real-Time Operational Telemetry & Anomaly Platform
A polyglot distributed system in Java/Spring Boot, Python/FastAPI, and React. Telemetry flows through Redis Streams consumer groups (XAUTOCLAIM fault tolerance, idempotency, DLQ) into a TimescaleDB hypertable; two-layer anomaly detection (z-score + EWMA) and Holt-Winters forecasting that predicts threshold breaches before they happen. SSE live stream, ack/resolve alert lifecycle, a self-scoring forecast scorecard, and full containerization in a single command.
- Java
- Spring Boot
- Python
- FastAPI
- React
- TypeScript
- Redis Streams
- TimescaleDB
- Docker
Çiftlik Pro
Multi-Tenant Farm Management SaaS
A multi-tenant SaaS with dual-layer tenant isolation via PostgreSQL Row-Level Security (FORCE + WITH CHECK) and a Prisma extension. Four-role RBAC (Admin/Worker/Vet/Accountant), single-transaction public sign-up (tenant + admin), token-based staff invitations, FREE/PRO plan limits, and Stripe subscriptions. Self-service data export + account deletion for regulatory compliance, 277 unit + 7 E2E tests.
- Next.js
- TypeScript
- Prisma
- PostgreSQL
- RLS
- Stripe
- Auth.js
RippleChat
Real-Time Community Chat Platform
Real-time messaging over WebSocket/STOMP with threads, reactions, and presence. End-to-end encryption (X3DH + Double Ratchet), TOTP-based 2FA, session/device management. WebRTC voice and video calls, Web Push, PWA/offline. Elasticsearch-powered search that gracefully degrades to a PostgreSQL fallback.
- Spring Boot
- Java
- React
- TypeScript
- PostgreSQL
- Redis
- Elasticsearch
- WebSocket
- WebRTC
SubTrack
Subscription & Expense Tracker
TypeScript monorepo that shows monthly/yearly subscription costs in multiple currencies. 2FA, Google + GitHub OAuth, server-side JWT revocation, spending forecasts, 53 tests, Docker + GitHub Actions CI/CD.
- React
- TypeScript
- Node.js
- Express
- PostgreSQL
- Prisma
Experience & Certificates
My software journey shaped by education and continuous growth.
Education & Experience
Computer Science
University of the People
Bachelor's studies in computer science fundamentals, algorithms and software engineering.
Full-Stack Web Development
Workintech
Intensive, project-based full-stack program covering React, Node.js, PostgreSQL and modern web architectures.
Certificates
PostgreSQL için SQL Dili
BTK Akademi
Frontend Developer (React)
HackerRank
React (Basic)
HackerRank
JavaScript (Basic)
HackerRank
IELTS Academic
6.0
AI for Beginners
HP
B1 English for Developers
freeCodeCamp
Let's build something together
For a new project, a collaboration, or just to say hi — the inbox is always open.
Reach out directly