Open to opportunities

Vladimir Mosienko

@vladimirmosienko

Senior Python engineer, de facto tech lead. I make legacy systems safe to change: tests first, then migration, complexity measured.

Armenia

Message

What I'm looking for

A remote product company with real legacy debt and room to shape technical direction. Senior or Staff IC role with cross-team scope: migrations, reliability, test and CI foundations, design docs. Python backend. I contract B2B as a registered Armenian sole proprietor, need no sponsorship, and have worked US East hours for over a year.

At Software Country, I led the migration of 82% of a decade-old Python 2 codebase to Python 3.12. I designed it as a strangler fig, so both versions can run simultaneously and rollback is a switch rather than a procedure; production cutover is pending the client's decision.

At Bitbanker, I designed and implemented the multi-tenant architecture for a banking platform. The migration covered 70% of the codebase with zero downtime, and tenant isolation was designed to fail closed.

At Nedra, I rewrote a broken economics engine that returned incorrect numbers and crashed on new data. The rewrite replaced code with high complexity with testable functional code, and computed more than 50 geological-economic parameters.

My work centers on making risky changes provable and reversible: characterization tests, static-analysis gates, and staged migrations. I’ve applied that approach across banking, insurance, oil and gas economics, and industrial workflows.

Experience

Work history, roles, and key accomplishments

Current

Senior Software Engineer

Current

Software Country

Mar 2025 - Present (1 year 8 months)

Own technical direction, architecture decisions and code review for a three-developer team. Led the Python 2 to 3.12 migration and rewrote the deployment pipeline.

Python 3.12 Flask Aiosql Pjrpc Pydantic MySQL Docker Compose OpenTofu Devenv BASH AWS

Independent Software Consultant

Jul 2024 - Mar 2025 (8 months)

Five client engagements across eight months, including two technical-debt remediation projects on legacy Python codebases and three integrations.

Python Legacy Code Characterization Testing Static Analysis Complexity

Senior Software Engineer

Bitbanker

Dec 2023 - Jul 2024 (7 months)

Designed and implemented the multi-tenant architecture behind the white-label product and delivered the migration. Maintained transaction correctness across the tenant boundary.

Python AIOHTTP PostgreSQL SQLAlchemy Alembic Multi tenancy Functional Programming

Senior Software Engineer

RateX Network

Jul 2023 - Nov 2023 (4 months)

Most senior developer on a greenfield build; owned backend technical direction for a team of five. Launched the MVP in three months from nothing.

Python PostgreSQL ELT Idempotent Loads Blockchain Indexing

Lead Engineer

Surgutneftegas

Jul 2022 - Sep 2022 (2 months)

Diagnosed the core problem as scientific calculations scattered across three runtimes and designed a hybrid architecture consolidating the scientific core into Clojure. Refactored one feature end-to-end as proof.

Clojure C#Oracle Functional Programming Architecture

Software Engineer

Nedra

Mar 2021 - Jan 2022 (10 months)

Rewrote the broken economics engine, computing 50+ geological-economic parameters. Coached a team of ten and mentored eight student interns.

Python 3 fastAPI SQLAlchemy Pandas PostgreSQL MongoDB Redis Kafka Kubernetes

Web Developer

Alliance of Safety Assistance Professionals

Jul 2018 - Jan 2021 (2 years 6 months)

Sole developer with direct access to management; owned the rewrite, infrastructure, monitoring, specifications and frontend prototypes. Stabilised the legacy system and rewrote it onto Python 3 / Django.

Python Django PostgreSQL NixOS NixOps Prometheus PGP Encryption

Web Developer

Information Technologies and Communications

Mar 2016 - Jun 2018 (2 years 3 months)

Requirements analysis, database design and integration across 30+ custom projects. Challenged a client's stated requirement and proposed a Telegram bot instead of a native app.

Requirements Analysis Database Design Integration Telegram Bots

Education

Degrees, certifications, and relevant coursework

Tyumen State University

Specialist's Degree, Physics

2004 - 2009

Completed a five-year Specialist's degree in Physics, with an additional qualification as a Lecturer. The degree is recognized as Master's-equivalent (EQF level 7) in most European frameworks.