Portfolio

vending-esp32-monobank — IoT Coffee Machine Monobank Acquiring Controller

Solo Embedded & Cloud IoT Architect · Sep 2026

Zero-monthly-fee IoT telemetry and payment bridge for commercial Rheavendors coffee machines: customer scans a dynamic Monobank QR on the machine, Cloudflare Worker receives the payment webhook, and dispatches a TLS-encrypted MQTT pulse to an ESP32 microcontroller with optocoupler isolation, triggering the exact beverage dispense without touching the internal logic voltage. Zero subscription fees, direct FOP settlement.

ESP32C++Cloudflare WorkersServerlessMonobank Acquiring

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site-security-cleanup — Malware Remediation and CMS Hardening

Solo Security Engineer / Webmaster · Sep 2026

Emergency malware cleanup and hardening for compromised WordPress, Joomla, and OpenCart stores: isolated staging triage, heuristic backdoor and web shell removal, hidden SEO redirect cleanup, database sanitization, PHP 8.2+ compatibility migration, WAF deployment, upload folder execution locking, and Google Safe Browsing blacklist removal with 100% data preservation.

WordPressJoomlaOpenCartPHP 8.2+MySQL

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fastshop — Fast Mobile-First OpenCart Store

Solo Creator / Architect · Sep 2026

A 30,000-product OpenCart store built as an overlay on stock OpenCart: faceted filters with counts and one canonical SEO URL per filter state, a one-page checkout with a Nova Poshta city/branch picker, Redis cache, WebP and a lean theme. Against stock OpenCart on the same data: catalog page 34 ms to 10 ms, search 267 ms to 5 ms, Lighthouse mobile 100 with a 19–28 KB page. 37 end-to-end checks.

OpenCart 3OpenCartPHP 8.3MySQLRedis

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crmbridge — Shop, Telephony and Parcels in One CRM

Solo Creator / Architect · Sep 2026

Connects a shop or Telegram bot, Binotel telephony and Nova Poshta to a SalesDrive CRM: one deal per order even when the site retries or the CRM loses a reply, caller cards for managers, missed calls as leads, and parcel statuses that move the funnel forward only. 250 tracked parcels take 3 Nova Poshta requests. 25 tests under the race detector.

GoSalesDrive APIKeyCRMKeepinCRMBinotel

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fiscalgate — Payments to Checkbox Fiscal Receipts, Exactly Once

Solo Creator / Architect · Sep 2026

Turns confirmed Monobank and LiqPay payments (and cash on delivery) into Checkbox PRRO fiscal receipts exactly once: 300 orders × 4 concurrent webhook copies give exactly 300 receipts, a lost register reply never doubles a receipt, prepayment plus cash on delivery becomes one receipt with two tenders, and refunds become return receipts. Shift and Z-report on schedule. 26 tests under the race detector.

GoCheckbox APIПРРОФіскалізаціяCheckbox

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feedsync — Supplier Feeds to Marketplace Price Lists

Solo Creator / Architect · Sep 2026

Turns supplier price feeds (YML/XML, CSV, JSON) into Rozetka and Prom.ua price lists and syncs an OpenCart product table: streaming read, every published file re-validated independently, atomic publish. 25,000 offers in about 1.5 s and 36 MB; 100,000 in 6–7 s; a repeat OpenCart sync changes nothing (≈25 ms).

Goencoding/xml streamingXML/YMLProm.uaRozetka

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Luxury Fashion E-commerce (Shopify)

Freelance Backend Engineer / AI Integration · Sep 2026 — ongoing (Stage 1 of 3)

Building an AI ad-testing loop for a Shopify luxury-fashion store: Claude turns live product and order data into offer/angle/hook hypotheses, Higgsfield renders the creatives, and the system assembles Meta campaigns — created paused, with hard spend caps — then scores winners by reconciling against real Shopify orders, not the ad platform's own pixel. Stage 1 of a 3-stage engagement, in progress.

GoShopifyShopify GraphQL Admin APIPostgreSQLMeta Marketing API

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bid-triage — AI Bid-Noise Filter, Built to Order

Solo Architect (Bespoke Engagement) · Sep 2026 (concept, available to build)

A bespoke bid-screening engagement for freelance-platform clients drowning in AI-generated proposals: instead of detecting authorship (an arms race that favors the generator), it prices the interaction — a deterministic fluff-strip filter, then one deadline-gated canary question a real practitioner answers in a line and a generic pipeline can't. The same mechanic generalizes to any high-value, low-volume screening decision (B2B tenders, security-disclosure triage) — scoped conservatively per client, not sold as a shared SaaS product.

GoLLM Structured OutputDeterministic Pre-FilteringSession-Based Browser Automation

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v2v-demo — Multi-Vertical Voice AI Concierge for Telegram

Solo Creator / Architect · Aug–Sep 2026 (ongoing)

A bilingual (UK/EN) Telegram voice concierge framework running five independent business assistants (dental, auto, real estate, cleaning, translation) behind one inline picker, sharing a single grounding-gate core. An automated scenario-probe tool caught a real safety-relevant bug (a sedation request getting scheduled as a routine booking) before it reached a user. 124 passing tests, one main dependency. Live demo: message @v2v_demo_bot on Telegram.

GoTelegram Bot APIOpenAI WhisperOllamaElevenLabs

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landing-turnkey — Turnkey Landing Page Designs

Solo Designer / Developer · Aug 2026

Two original landing-page design directions for the common one-page-site request: a bright, discount-driven product page and a dark, portfolio-style business/services page, each built around a single call to action and a lead-capture form.

HTMLCSSResponsive Layout

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ragline — AI/RAG Telegram Support-Bot Backend

Solo Creator / Architect · Aug 2026

AI/RAG Telegram support-bot backend: Postgres full-text search retrieval, a pure escalate/generate/cache decision that never repeats a low-confidence guess (even from its own cache), and a version-gated answer cache that invalidates on document edits. Proven live: a real retrieval bug (stopword-driven false matches) found and fixed against seeded fixtures, then a document edit correctly forced regeneration instead of serving a stale cached answer.

Gochipgx/v5PostgreSQLJWT

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subgate — Telegram Paid-Channel-Access Backend

Solo Creator / Architect · Aug 2026

Telegram paid-channel-access REST API: idempotent payment-webhook ingestion (gateway redeliveries absorbed via a UNIQUE constraint) and a membership state machine (active/grace/expired) that survives a concurrent expiry sweep. pg_advisory_xact_lock(subscriber_id, channel_id) serializes renewals against sweeps. Proven live: 10 concurrent identical webhook deliveries produced exactly 1 payment row; 5 concurrent renewals racing 5 concurrent sweeps landed deterministically active.

Gochipgx/v5PostgreSQLJWT

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geopulse — GPS Fleet-Tracking Backend

Solo Creator / Architect · Aug 2026

GPS fleet-tracking REST API with exactly-once geofence enter/exit detection from a position stream that duplicates and reorders — the real failure mode of GPS trackers. pg_advisory_xact_lock serializes concurrent pings per vehicle; PostGIS ST_DWithin handles containment. Proven against direct database state: a burst of concurrent/rapid pings produced zero spurious events across the full test session.

Gochipgx/v5PostgreSQLPostGIS

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slotwise — Appointment Booking Backend

Solo Creator / Architect · Aug 2026

Appointment-booking REST API where double-booking prevention is a Postgres EXCLUDE constraint (tstzrange + btree_gist), not an application-level check — no race window under concurrent requests. Proven live: two simultaneous overlapping booking requests against the running server return exactly one 201 and one 409. Booking state machine, Telegram reminders with a zero-credential fallback.

Gochipgx/v5PostgreSQLJWT

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fleet-crm — Fleet/Logistics CRM Backend

Solo Creator / Architect · Aug 2026

Fleet/logistics CRM REST API — JWT auth, a checked work-order state machine (not a free-form status column), invoicing gated on completion, and a telematics webhook. Found and fixed a real cross-entity bug (a partial-update fix that prevents vehicle data loss on every status change) before the first commit — verified end-to-end via a live docker compose run, not just unit tests.

Gochipgx/v5PostgreSQLJWT

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tumanomir — CLI for Measuring AI-Spec Ambiguity

Solo Creator / Architect · Jul 2026 (25 days)

Go CLI implementing a published methodology for measuring AI-spec ambiguity as three metrics (K_drift, D_const, D_pair). 66 commits, zero reverts, gates its own specification in CI. Rewrote the K_drift scanner for a 233x allocation reduction; found and documented a naming-noise floor in the generation-spread metric.

GoOllamaAST AnalysisSpearman CorrelationYAML

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fix-review — Multi-Agent PR Review Pipeline

Solo Creator / Maintainer · Jun — Aug 2026 (ongoing)

Multi-agent PR review pipeline: fans a diff out to 3 parallel models with a read-only 5-tool CLI fallback cascade, then a Claude arbiter verifies each finding against real repo state before acting. In production since June 2026: 22 PRs reviewed, 69 review rounds, 81 raw findings but only 2 confirmed fixes — replaced a permission-bypass CLI tier with a verified read-only cascade.

Claude Code SkillBashOllama Cloud/Local5 External CLI AgentsGitHub CLI

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Sales CRM Platform

Freelance Full-Stack Engineer / AI Integration · Mar — Jun 2026

Built out a modular, conversation-first sales CRM across 1,366 commits in 3 months — AI-powered reporting through a provider-fallback gateway (Gemini → OpenRouter), a deterministic decision-billing ledger, lead ingestion/enrichment pipelines, and org-level access control. ~123K LOC across frontend and edge functions, 201 test files, 23 production cron jobs.

ReactTypeScriptViteTailwind CSSSupabase

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Gym Operations SaaS

Freelance Full-Stack Engineer / AI Integration · Mar — Jun 2026

Took over and substantially rebuilt a gym-cleaning operations platform after its no-code MVP stage. Delivered mobile-first cleaner workflows with AI photo validation, automated escalation triggers, and multi-provider LLM failover across 991 commits in 3 months — 42K LOC, 474 passing tests, zero npm vulnerabilities.

ReactTypeScriptViteTailwind CSSSupabase

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Ukrainian Consultancy

Solo Architect / Engineer / DevOps · Apr — Jun 2026

Conversational AI assistant (Telegram bot) for a Ukrainian application-writing consultancy. RAG + LLM fills Excel templates while preserving formula chains. 8-week solo delivery: 65 sessions completed, 100% Excel artefact validity, 22% escalation rate.

GoPostgreSQLpgvectorOllama bge-m3OpenRouter

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Micromobility Startup

Freelance Backend Engineer / AI Integration · May — Jun 2026

Built a voice AI agent automating 80% of 20,000 monthly support calls for a micromobility company. Delivered in 24 days: Go backend, Binotel webhooks, Whisper STT, GPT-4o-mini function calling, ElevenLabs/Azure TTS, Redis session state.

GoBinotelOpenAI WhisperGPT-4o-miniElevenLabs

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CloudBees CD/RO

Senior Software Engineer / Plugin Developer · Nov 2018 — May 2019

Developed enterprise DevOps platform components for CloudBees CD/RO serving Fortune 500 clients. Created 50+ reusable plugins in Java, Groovy, and Perl, reducing code duplication by 60% and achieving 95% automated test coverage.

JavaGroovyGoPerlDocker

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PortaSwitch / PortaOne

Team Lead / Senior Backend Developer · Mar 2013 — Mar 2018

Led Kyiv development team for 5+ years building core components for PortaSwitch BSS, Billing, and Softswitch platform serving MNO/MVNO/MVNE, cable, VoIP, and IoT providers. Architected billing solutions with 99.9% system reliability.

PerlLinuxMySQLPostgreSQLVoIP

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Mail.UA

System Architect / Head of System Development Department · Jun 2011 — Jun 2014

Architected complete redesign of enterprise email platform mail.ua serving 1M+ active users. Managed 20+ backend engineers through 3-year platform transformation, transitioning from Waterfall to Agile with automated testing pipelines.

PerlShell ScriptingMySQLPostgreSQLLinux

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