Istanbul · available for freelance work
Backend engineer with 5+ years in TypeScript, Node.js and event-driven architecture. At Marti I moved 30+ services into a single Nx monorepo and split a shared database per service, cutting over on a live fleet without downtime. On the side I build and operate relay.patates.tech alone.
Services
integration
WhatsApp Cloud API, Messenger and Instagram messaging wired into your product: webhook processing, message templates, number and app review, delivery and read receipts, rate limits. I run this in production for a multi-tenant SaaS.
architecture
Service boundaries, event flows, database decomposition and migration plans that do not require downtime. If you have a monolith that outgrew itself or services tangled into each other, I draw the ownership lines and the route out.
product
End to end, from the API to the interface: TypeScript, Node.js, PostgreSQL, React. Multi-tenant SaaS, internal operations panels, customer portals — including setup, deployment and CI/CD.
mobile
Mobile apps on the same backend: authentication, notifications, offline behaviour and store release. One person holds both ends, so nothing is lost between the interface and the API.
delivery
Setting up how software gets built: hiring plan, team topology, ownership boundaries, code review and CI standards, release process. The same work I led as technical lead across a 10+ engineer backend organisation.
automation
Internal workflows automated: CRM, inbox and third-party APIs joined into one pipeline, scheduled jobs, steps that still need a human to approve. Turning manual work into something that runs — and keeping it running.
Selected work
B2B CRM and omnichannel inbox for Turkish insurance agencies. Multi-tenant architecture with WhatsApp Cloud API integration, webhook processing and background job pipelines, built with KVKK compliance in mind. Fastify, TypeScript, PostgreSQL, Prisma, BullMQ, Redis, React 18/Vite, Nx monorepo — self-hosted on Hetzner with Docker and CI/CD.
built · deployed · operated solo
Ride-hailing and micro-mobility platform carrying hundreds of thousands of trips a day. I proposed the consolidation of 30+ independently deployed microservices into a single Nx monorepo and drove it to completion as technical lead; decomposed the shared database into per-service databases; designed Kafka event flows for trip lifecycle and driver-passenger operations; shipped H3 geospatial indexing that cut proximity-query latency. I also built an AI-native development harness that let coding agents work safely across all 30+ services.
30+ services · 10+ engineers · zero-downtime cutovers
Designed and delivered the backend for a multi-tenant SaaS serving 30+ enterprise brands — including D-Smart and Petrol Ofisi — across chatbots, CRM and reporting. Event-driven microservices in NestJS, TypeScript, PostgreSQL and MongoDB, applying DDD and SOLID; RabbitMQ and Kafka for asynchronous workflows.
30+ brands · scaled past 30 tenants
Built RPA integrations between enterprise systems, automating data synchronisation to increase client process productivity by 40% and reduce system downtime by 25%.
+40% process productivity · −25% downtime
How I work
We start by writing down the problem and what finished looks like. What is out of scope goes in the same document. Surprises surface there, not on the invoice.
Infrastructure, deployment, CI/CD and behaviour in production are part of the job, not somebody else's problem. I operate my own SaaS alone, so I know what breaks after launch.
The repository, the documentation and the handover are yours. I leave a codebase your own team can continue — not a box that needs me to open it.
Stack
Contact
An integration, a product from scratch, or a question about how your team should work. Write down the problem and when you need it — I answer within two days.
contact@sinancoskun.dev