Laravel · PHP · Python · API · FinTech · Production

Senior Backend Engineer for Complex Systems

I design and develop backend systems, CRM platforms, FinTech solutions and API integrations where business logic, data integrity and reliability matter.

I work with both new and existing production systems — from architecture and development to troubleshooting, stabilization and long-term maintenance.

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Core expertise

  • CRM & complex business systems
  • FinTech, payments & crypto
  • API integrations & automation
  • Production engineering & troubleshooting
  • Laravel / PHP backend development
  • AI / RAG within business systems

When a project needs engineering ownership

I am most useful when a project involves more than an isolated feature: complex business rules, several integrations, financial operations, critical data or an existing production system.

I examine the architecture and current workflows, identify failure points and propose a solution that can be maintained and developed over time.

Taking over an existing production system

I can get up to speed on an unfamiliar codebase, trace a failure across the application and infrastructure, fix its root cause and continue developing the system. The work can include recovery, stabilization and ongoing support.

Production stack: Laravel / PHP · Python · Node.js · Linux · Docker · Nginx · AWS · MySQL / PostgreSQL · Redis

Technical interfaces: Vue / Nuxt / React / Alpine for CRM workflows, dashboards, admin panels, forms, tables and filters.

What I build

CRM & business systems

CRM, ERP and internal platforms with complex workflows, roles, documents, statuses, audit trails, automation and business rules.

FinTech, payments & TON

Payment processing, subscriptions, recurring payments, transactions, internal balances, P2P, reconciliation, TON / Jetton and financial-service integrations.

Backend & API integrations

Laravel / PHP, Python and Node.js. REST APIs, webhooks, queues, retries, rate limits, data synchronization, permissions, logging and reliable error handling.

Production & infrastructure

Linux, Docker, Nginx, AWS, MySQL / PostgreSQL and Redis. Queues, workers, cron, API troubleshooting, logs, tracing, monitoring and root-cause analysis.

AI / RAG in business systems

LLM APIs, RAG, embeddings, vector databases, local models and AI pipelines. Document processing, structured extraction, evaluation and human review.

Marketplace automation

Ozon, Wildberries and external services: product data, stock, prices and order synchronization, integrated with CRM and business workflows.

Latest articles and engineering notes

MCP + RAG: How AI Turns Data into Clear Answers, Tables and Charts

How to combine MCP and RAG for document search, Telegram conversation analysis, financial data and telemetry, with practical examples.

MCP for Websites: Audits, Product Selection and Business Data for AI Clients

A practical guide to website MCP: data audits, product selection, support, analytics, security and real ifreework.com scenarios.

“Let’s hire AI bots and make support cheaper.” What could go wrong?

A simple balance transfer took about five hours. Here is why chat history cannot replace task state and what backend architecture AI support needs.

Jev vs. Five LLMs: Selection Quality, Latency, and Cost for Building RAG Systems

Which model fits each RAG task: bulk filtering, fast review, or strict source selection? We compare Jev and five LLMs on 200 projects and show how aggregators such as apixly.ai help run the evaluation.

Deye Inverter Data Every Minute: Local Monitoring Without the Cloud

A practical Deye monitoring setup: Solarman V5 and Modbus, a minute-level Python collector on Synology, an offline spool, a secure Laravel API, and charts.

Jetton Withdrawals: Reservations, Confirmation and Ledger

How to reserve Jetton for withdrawal, release it after failure and avoid duplicate deductions.

TON Deposits: Idempotency and Exact Credit

How a verifiable transaction ID, balance update and ledger prevent a retried webhook from double-crediting TON.

About me

My name is Andrey Zubar. I am a Senior Backend Engineer / Software Architect with over 15 years of experience.

I specialize in complex backend systems, CRM platforms, FinTech, API integrations and production infrastructure. Laravel / PHP is my main backend stack, alongside Python and Node.js. I use AI / RAG as part of the architecture when it serves a concrete business need.

I am particularly interested in systems where data integrity, complex business rules, integrations, financial operations and predictable production behavior matter.

More about me · Client reviews


Let’s discuss your project

Tell me what you would like to build. I will reply by email.

Or message me on Telegram @ifwcom