For a year I was the only engineer at a Berlin B2B SaaS: architecture, code, releases, incidents. I rebuilt the product and carried the B2C → B2B pivot that took the company to profitability.
02
Multi-tenant backends
Designed a multi-tenant PostgreSQL schema and 100+ REST endpoints. New B2B clients were onboarded through configuration — 15+ of them, zero code changes per client.
03
Auth & access
RBAC, JWT in httpOnly cookies, bcrypt. Replaced ASP.NET Identity in a live system without losing a user.
04
Payments & documents
Stripe subscription billing, generated PDF offers, invoices and receipts with embedded Stripe payment, Lexware accounting and SendGrid email workflows.
05
Infrastructure
Ran production alone: Linux VPS, Docker, Nginx, certbot, PM2, systemd, GitHub Actions. Cut page load from 3–4 s to ~150 ms. This site is self-hosted the same way.
06
Applied AI
Two Python microservices in production — YOLO object detection and OCR over a 300+ item catalog, 96% / 99% accuracy on plain CPUs. Plus OpenAI / Anthropic API integrations.
Case studies
Real products, real constraints, one engineer.
No todo apps. Each case shows the problem, what I built, how it fits together and what changed.
case 01 · Relofair GmbH · Berlin · sole engineer04/2025 – 03/2026
Rebuilt a legacy app and turned it into a multi-tenant B2B CRM
Problem
Relofair ran on a legacy .NET application built for consumers. The business was pivoting to B2B — selling the platform to partner companies — and needed a CRM that could serve many clients from one codebase. There was one engineer.
What I built
Rewrote the product on Next.js / TypeScript with Node.js and ASP.NET Core services behind it
Multi-tenant PostgreSQL schema and 100+ REST endpoints; tenant behaviour driven by configuration
Role-based access control across tenants
Generated PDF offers, invoices and receipts with an embedded Stripe payment; Stripe subscription billing
SendGrid email workflows, Lexware accounting, Google Analytics / Ads integrations
My responsibility
Everything technical: architecture, data model, backend, frontend, CI/CD, releases and incident handling.
✓15+ B2B clients onboarded through configuration only
✓Page load from 3–4 s down to ~150 ms
✓The B2B pivot brought the company to profitability
Tech
Next.js
TypeScript
Node.js
ASP.NET Core
PostgreSQL
Prisma
Stripe
SendGrid
Lexware
Docker
Nginx
PM2
case 02 · Relofair GmbH · applied AI2025
Photo in, structured catalog items out
Problem
Customers had to pick their items by hand from a catalog of 300+ entries. It was slow and error-prone, and it was the step where people gave up.
What I built
Python object-detection service (YOLO), restricted to the catalog’s classes, running on CPU
Python OCR service
Both behind the main API, so the product just receives catalog IDs and quantities
My responsibility
Designed the service boundaries, fitted detection to the catalog’s classes, integrated them into the product and deployed them next to the rest of the stack.
Architecture
input
Photo / voice
api
Main API
services
Detection (YOLO)
OCR
output
Catalog items → offer
architecture · simplified
Result
✓96% detection accuracy, 99% OCR accuracy
✓Ran on existing CPU servers — no GPU bill
Tech
Python
YOLO
OCR
Docker
REST
case 03 · Vechnost · production migration04/2026 – 09/2026 · part-time
Moved a live backend from ASP.NET Core to NestJS without touching the data
Problem
A production catalog site on ASP.NET Core 8 / Entity Framework. The goal: a TypeScript stack that is cheaper to maintain — while every product, image and admin account in PostgreSQL stays exactly where it is.
What I built
NestJS 11 + Prisma mapped onto the existing EF Core schema instead of migrating it
Replaced ASP.NET Identity (7 tables, cookie auth) with JWT in an httpOnly cookie, bcrypt and roles
Rebuilt the React admin panel
Fixed production bugs: mixed content from absolute image URLs in the DB, latin1-corrupted Cyrillic filenames
Linux VPS with Nginx, a systemd service and a health-check timer
My responsibility
Solo: migration plan, backend, auth, admin UI, deployment and cut-over. In 2024 I had built the original version, which took the business online — sales grew 400% after launch.
Architecture
client
React storefront
React admin
edge
Nginx · TLS
api
NestJS 11 · JWT
data
PostgreSQL (schema kept)
architecture · simplified
Result
✓Zero data migration, zero lost records
✓One language across the stack, simpler ops
✓Sales +400% after the original 2024 launch
Tech
NestJS
Prisma
PostgreSQL
React
Nginx
systemd
ASP.NET Core
EF Core
Also
RentAGym · 2023–2024
B2B startup, acquired at MVP stage. ASP.NET Core backend with Clean Architecture, tenant/landlord permissions, booking-conflict resolution, SignalR real-time.
Sensor Hub · 06/2026 – now · in progress
IoT telemetry: ESP32 → MQTT (Mosquitto) → NestJS ingestion → PostgreSQL / Prisma, JWT auth with per-user device ownership, Last Will liveness, Docker Compose, Next.js dashboard.
SaM Solutions · 2022–2023
Internship: 20+ REST endpoints on ASP.NET Core and a background service aggregating 24-hour data streams.
BSUIR · Research Assistant · 2020–2023 · part-time
University lab run in partnership with Yandex: automated testing of algorithm implementations on large inputs against reference solutions, test-run statistics in Python (pandas) and MATLAB.
Terminal CV
Prefer a shell?
Same CV, different interface. Type help or tap a command.
arti@berlin: ~/cv
❯ whoami
Artsiom Abozny — everyone says Arti. Full-Stack / Backend Engineer based in Berlin. 3+ years in production; the last one as the only engineer of a B2B SaaS.
Contact
Want to build something together?
Currently looking for my next engineering role in Berlin or remotely in Germany. EU Blue Card — no sponsorship needed.
English B2 · German B1 (course ongoing) · Russian, Belarusian native