javohir.dev
KOENUZ

Backend Developer & PostgreSQL DBA

I build backends where the numbers add up.

I'm Javohir, a backend developer who builds reliable systems around PostgreSQL. I designed and deployed a double-entry ledger, a PostgreSQL monitoring platform, an IoT pipeline validated with real ESP32 sensors, and a live-commerce platform built on Saga and Outbox. My strengths are database design and performance tuning, concurrency control, and transactional integrity. Over four years I have worked with NestJS and Java/Kotlin/Spring Boot, including at Sigma Software and LeverX Group in Uzbekistan, and as a freelance backend and database developer for manufacturing, F&B and AI service companies in the UAE, Hong Kong and Bangladesh.

View projectsView resumeGitHub

How numbers are shown on this site

Measured
Shown together with evidence such as a k6 report or screenshot.
Design target
A condition the system was built around from the start.
From code
A value anyone can check in the repository.
Not measured
Values not yet measured are never estimated; they stay —.

Projects

See all projects

Skills and proof

Shows which project you can check each skill in.

PG InsightLedgerCoreSmart FarmFlashDropLiveCommerce
Concurrency control
Distributed transactions (Saga, Outbox)
Data integrity
PostgreSQL performance and operations
Payment integration
Real-time communication
IoT and embedded
Authentication and authorization
Load testing
Deployment and operations

Experience

Backend Developer (remote, Tashkent)

Sigma Software

2024.09 – 2025.08

A global IT services company founded in Ukraine (2,000+ specialists in 12 countries). On a team of six (3 backend, 2 frontend, 1 QA) I owned the backend APIs and the database schema. Java, Kotlin, Spring Boot, PostgreSQL, Redis, Docker, GitHub Actions, AWS, Kubernetes.

  • Order list API p95 1.4 s → 210 ms: added a composite index and merged N+1 queries into a single JOIN (Grafana p95 before/after)
  • Redis cache cut repeated read queries to the primary database by about 45% (pg_stat_statements calls before/after)
  • Took part in a Primary–Standby HA setup on streaming replication; failover to the standby completes in 5–10 s
  • Designed order and invoice APIs for a European client in Java/Kotlin and Spring Boot, and introduced versioned Flyway migrations

Backend Developer & PostgreSQL DBA (remote, Tashkent)

LeverX Group

2022.10 – 2024.05

An international IT company building SAP-based software and web, mobile and cloud solutions (1,500+ employees). On a team of eight I owned the integration services, reporting APIs and the database. Node.js, NestJS, PostgreSQL, REST, Docker, Redis, AWS.

  • Completed a PostgreSQL 13 → 15 major upgrade with logical replication and zero downtime
  • Built an integration service for data exchange between internal systems, removing manual integration work
  • Added pagination and batch export to large reports so they are processed in chunks without overloading the server
  • Wrote unit and integration tests wired into CI, and optimized slow database queries

Backend & Database Developer (remote)

Freelance

2021.11 – 2025.09

Project-based work solving database performance, security and scaling problems for overseas clients (16 months in total).

UAE

Industry
Manufacturing · 2021.11 – 2022.04 (6 months)
Problem
As data grew, end-of-day production reports opened slowly and managers waited a long time.
What I did
Analyzed slow queries with EXPLAIN ANALYZE and rewrote them, added indexes, and introduced materialized views for the heaviest frequent reports.
Result
Report load time 12 s → 0.8 s (~15x); overall database query load dropped

Hong Kong

Industry
Restaurant / F&B · 2023.01 – 2023.04 (4 months)
Problem
Some database users in the ordering system had far more privileges than their jobs needed, a real security risk.
What I did
Redesigned permissions with RBAC, restricted table access with row-level security, and set up daily backups with a recovery procedure.
Result
Unneeded superuser connections 7 → 0; restore from backup tested at under 15 minutes

Bangladesh

Industry
AI services · WellDev Bangladesh Ltd. · 2025.03 – 2025.09 (6 months)
Problem
The table storing AI model results grew fast and INSERTs slowed down.
What I did
Split the table with monthly range partitioning and introduced an archiving strategy for old data, so live traffic touches only the partitions it needs.
Result
INSERT p95 320 ms → 45 ms (~7x); active data 180 GB → 22 GB

Client details are limited to what my contracts allow.

Education

Seowon University

Bachelor of Business Administration, Global Business

2022.08 – 2026.08

MIT Group (DevEx Academy)

Backend development bootcamp

How I work

  1. 1Pin down requirements and constraintsI first write down what must hold: consistency, latency, cost.
  2. 2Design and record decisionsAlternatives and trade-offs go into decision records (ADRs).
  3. 3Build with testsBehaviour is verified with integration tests against a real PostgreSQL.
  4. 4Deploy and monitorShip through CI/CD and collect runtime metrics.
  5. 5Measure and publishMeasured numbers are published with their evidence.

Questions recruiters ask

Can you work in Korea?

Yes. I have already changed from a D-2 (student) visa to a D-10 (job-seeker) visa. Once hired, I will change my status to an E-7 (special activity) visa. E-7 is the work visa a Korean company uses to hire a foreign professional for an occupation designated by the Ministry of Justice, software developers included; the change is filed at the immigration office with the employment contract and supporting documents from the company.

Can you work in Korean?

Yes, I communicate and work in Korean without problems. I hold TOPIK II Level 6, the highest level (451/600, reading 200/200), from the 14th TOPIK IBT in September 2026. The score report is below, and its document number can be verified on the TOPIK website.

TOPIK II Level 6 score reportViewDownload PDF
When can you start?

From November 1, 2026.

Your degree isn't in computer science. Is that a problem?

I studied Global Business, so I don't have a CS degree. I filled in the fundamentals systematically through books such as 'PostgreSQL Without Getting Stuck', 'Admin Stories for PostgreSQL DBAs', 'Home IoT with Raspberry Pi' and 'Raspberry Pi 5 for Edge Computing and Physical AI', and applied each one straight away in projects that I shipped to production. I also gained hands-on experience at Sigma Software and LeverX Group and as a freelance backend and database developer for overseas clients. My business background is actually a strength: I am good at turning domains with complex business rules, such as ledgers, POS and commerce, into precise data models.

What role and work arrangement are you looking for?

A full-time backend developer or database (PostgreSQL) role. I prefer Seoul or Gyeonggi-do.

Why a Korean company?

Studying in Korea, I saw up close how fast Korean IT services move and how high their quality bar is, and I prepared to join a Korean company to grow in that environment. Working remotely with overseas clients taught me to document decisions and the reasons behind them; every project of mine has a README and diagrams so anyone can pick the work up easily.

I'm looking for a team to join.

For hiring questions, email me or use the form below.