YDyusufdariyemez.com

Portfolio

Yusuf Erkan Darıyemez — Senior Backend Developer. Work history, company projects and open source — the long version.

Experience

Senior Backend Developer / Team Lead — ITT Teknoloji A.Ş.

2022 – 2026 · Gebze / Kocaeli

Backend infrastructure for ERP, CRM, CMS, donation management, accounting, reporting and payment modules.

Designed and built backend infrastructure with Go, Bun ORM and PostgreSQL
Led a 7-person cross-functional team (3 backend, 2 frontend, 1 mobile, 1 analyst); drove mentoring and code review
Established team-wide backend standards: layered handler/service architecture, ORM conventions, naming rules, migration practices
Improved reporting and heavy-query performance through PostgreSQL schema design, query optimization and data modeling
Managed deployment and operations with Docker, Kubernetes, Azure, AWS S3 and CI/CD; built asynchronous, scalable systems with Redis and RabbitMQ

Backend Developer — Hayrat İnsani Yardım Derneği

2020 – 2022

Backend-focused development for enterprise web applications.

Developed backend-focused features with Go, C#, .NET and Vue.js across analysis, design, development, testing and release
Built relational database designs, data models and reporting solutions
Supported DevOps, release and production environment management

Company projects

Built at the companies I worked for — described here, source private.

Aid360

Go · Bun ORM · PostgreSQL

Enterprise platform managing donations, project management, CRM, CMS, accounting, sponsorship and payment processes.

Led backend architecture and development of donation, sponsorship, accounting and reporting modules
Integrated Craftgate and Stripe payment providers plus third-party accounting systems for end-to-end financial flows
Built role-based authorization and multi-language content management with Keycloak
Developed an AI-powered OCR pipeline (Google Gemini) extracting data from invoices and documents
Built asynchronous background processing with RabbitMQ and a custom task scheduler; Redis cache and S3-compatible storage
Developed push, SMS and WhatsApp notification infrastructure and operational reporting dashboards

ITT SAR

Go/Fiber · Bun ORM · PostgreSQL

Multi-tenant platform managing teams, inventory, vehicles, warehouses and field operations for search & rescue organizations.

Designed and built the layered handler/service backend architecture
Developed advanced inventory management: hierarchical category/variant structures, assignment/transfer flows, QR-code equipment tracking
Built organization-based multi-tenancy, JWT authentication and role-based authorization
Developed an audit-log system capturing before/after values for all critical operations, plus dashboard reporting

Proje Yönetimi

Go/Fiber · Bun ORM · PostgreSQL

Project lifecycle platform: application, execution and closeout with financial reconciliation and document approval flows.

Developed multi-stage file approval/rejection flows for 20+ document and step types
Built multi-currency financial closeout, expense allocation and category-based reporting
Built a concurrent background-job system synchronizing with the CRM

İdari İşler

Go · Bun ORM · PostgreSQL

Corporate fleet & administrative operations system: 18 modules and 130+ API endpoints covering fleet, real estate, procurement and budgeting.

Designed and built the layered (handler/service/domain) backend architecture
Developed multi-level approval flows (state machine) varying by amount tier for procurement and vehicle requests
Implemented S3-compatible storage (MinIO/AWS), Mailgun email and NetGSM SMS integrations; JWT, soft delete and centralized error handling

Kurban · CRM · Saha Takip · Temsilci Takip · Sertifika · İK · Depo & Lojistik

Go · Bun ORM · PostgreSQL

Other modules and products delivered on the same stack.

Open source

Patterns I kept rebuilding in production, extracted into small, tested Go libraries. Every repo: MIT, CI, no dependency bloat.

Products

hookkeep — Self-hosted webhook inbox: receive, verify, persist, deliver with retries, replay anything. PostgreSQL-native, embedded Vue UI.
orderflow — Reference backend wiring a dozen of these libraries into one system: API, worker, reconciler and a full compose stack.

Tools

monup — terraform plan for monitoring: point it at a Docker host, it discovers what's running and generates a tailored Prometheus + Grafana stack as committable config.
prompt-guard — Lock your LLM feature's behavior in CI: committed golden snapshots, shape-normalized diffs, deterministic assertions.

PostgreSQL tooling

pg-plan-guard — Catch query plan regressions in CI, not at 3 AM: snapshot EXPLAIN plans into a committed lock file, diff their shapes on every PR.
data-watchdog — Your system is up; is your data alive? Freshness / volume / integrity checks for operational Postgres, read-only by design, every alert ships with evidence SQL.

Money & correctness

go-ledger — Double-entry accounting engine: integer money, balanced transactions, append-only journal.
go-reconcile — Payment / bank reconciliation engine.
go-idempotent — HTTP idempotency-key middleware (Postgres / Redis).

Infrastructure building blocks

redis-lock — Distributed lock done right: unique tokens, atomic Lua release, lease extension.
redis-eventbus — Typed, durable event bus on Redis Streams (at-least-once, consumer groups).
go-s3-storage — Practical S3 / MinIO / R2 layer: content-type detection, streaming multipart, presign, CDN URLs.
go-keycloak-auth — Keycloak JWT validation and net/http middleware with safe JWKS rotation.

Integrations

go-efatura — Turkish e-invoice (GİB, UBL-TR): document builder, schematron-derived validation, XAdES signing.
go-mailer — One Message model over Amazon SES + Mailgun: typed errors, composable retry & failover.
go-netgsm — Idiomatic Go client for the NetGSM SMS API.
go-trvalidate — Turkish ID / IBAN / tax number / phone validation with checksums.

All repositories on GitHub →

Skills

Languages: Go, C#, JavaScript, SQL
Backend: RESTful APIs, microservices, Fiber / Gin / Echo, .NET Core
Databases: PostgreSQL, MSSQL, MySQL, MongoDB
Data access: Bun, GORM, Dapper
Cache & messaging: Redis, RabbitMQ
DevOps & cloud: Docker, Kubernetes, Azure, AWS S3 / MinIO, CI/CD
Observability: Uptrace, structured logging (Zap), performance monitoring
Leadership: team leadership, mentoring, code review, Agile/Scrum

Education

B.Sc. in Computer Engineering — İstanbul Sabahattin Zaim University · 2019 – 2023

Building a system?

Write me about backend architecture, payment infrastructure or PostgreSQL.

yusuf.erkamyed@gmail.com