Sergey Vareyko

Summary

Software Architect with 15+ years of experience in designing and delivering scalable, high-performance enterprise solutions. Strong background in Java and modern software architecture, with deep expertise in distributed systems, microservices, cloud platforms, and system integration. Brings additional experience in modern frontend and mobile application development, allowing for a full product perspective across backend, web, and mobile ecosystems. Experienced in translating business requirements into reliable technical solutions, driving architecture decisions, and mentoring engineering teams. Committed to building maintainable, secure, and efficient systems that enable long-term business growth.

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Projects

Projects https://vareyko.com/projects

My old creativity Some network pages/portals that I created a really long time ago. All of them are hosted on free platforms, so there could be a lot of advertisements. Page for the video game Juiced: https://juiced.ucoz.net/ Video game clan site - CelestialHeaven - https://ch.do.am/ (the original idea was not mine, but the remaster was) Site for BattleRealms: https://battlerealms.ucoz.ru/ There were some others, but I don't remember them, so I'll add them later. https://vareyko.com/projects/old-projects Playlist updater Problem: When I download some music, it stays on the desktop for a while, then I move it to another drive, but the playlists containing those songs get broken. How it was solved before: Fix them manually or recreate the playlist. Final solution: A tool for fixing file paths; it takes a text file (playlist) and a folder as input for lookup. Technical side: Java 7, Swing https://vareyko.com/projects/playlist-updater Business Rules Validation Tool An application to check the validity of rules and search for possible issues. It uses logical analysis of custom expressions and configurations made for a specific client, detects issues in the real environment, and much more. At first, the tool was a browser extension; when the complexity of validation increased, it was moved to the backend. Very early look of the application in the browser https://vareyko.com/projects/brvt Environment Updater A special tool that speeds up the management of application instances for the local and remote environment. It is written in Java and has complete support for Windows and Linux machines. You can see the Component Monitor module in the picture, which provides quick actions for some of the microservices and their status. It checks the processes and ports of specified services and runs commands on the target system from which that info was obtained. It also has a tab for managing application-specific skins, which can be quickly replaced. https://vareyko.com/projects/env-updater Wallpaper Randomizer Problem: My new displays are connected via DisplayPort and go to sleep on disconnect, so wallpapers were shown from the top of the folder. How to solve: Randomize file names in that folder on screen lock. Solution: Windows Scheduler + WallpaperRandomizer. This application simply goes to a specific folder and randomizes the names of all supported files in it, using a timestamp and a random number. Link to GitHub: https://github.com/vareyko-itechart/WallpaperRandomizer https://vareyko.com/projects/wallpaper-randomizer Vareyko Family (old) This portal was developed to share the same domain name between me and my sister. The history of this domain name is not very long. Previously this domain was owned only by my sister - Tamara, but one day she forgot to pay for it and I bought it. Then I decided that I should create this portal for anyone who wants a nice domain name for their own portfolio. So, if you're reading this story - you are already here. Technical side This application was developed using Kotlin, Spring, and ReactJS for the UI. It's pretty lightweight and effective. Domains are handled by nginx and an NS record on the hosting side. Pages are optimized for most screen sizes, and the language changes immediately when selected in the menu. Any theming can be used. Post content supports various configurations. Images can be configured to be displayed in different ways, videos can be embedded, and even custom code can be placed. https://vareyko.com/projects/vareyko-family-old Bolimond Porfolio (old) Portfolio application with a gallery, customizable pages, and flexible configurations. It consists of two parts: a UI with Javascript/AJAX and a backend with JSP. UI pages are completely rendered on the backend, and AJAX calls receive complete HTML parts. On the initial call, current settings are loaded, and the page can be automatically refreshed if the version on the backend changes. Pages like 'ABOUT' can have their own style and can be edited in the Admin Panel. Animations and styles are compatible with IE6. UI available here: https://bolimond.com/ https://vareyko.com/projects/bolimond-old Tobo tobo.by — not a generic storefront, but a specific brand: TOBO_ceramics. Handmade ceramics (sculpture, home ceramics, masks, plus a sale section). Creator: Tamara Vareyko. The "about" text talks about clay as a language for the different facets of the self. Single-JAR e-commerce storefront and admin CMS. The Spring Boot backend serves both the REST API and the built Vue SPA (public storefront + admin panel) from one fat JAR, with built-in image processing, WYSIWYG content editing, rate limiting, and RU→ASCII slug generation. https://vareyko.com/projects/tobo Bolimond Personal portfolio/CMS site for artist Constantin Bolimond (bolimond.com): a public gallery SPA paired with an admin panel built around a GrapesJS visual page builder for freeform layout editing, backed by in-house libraries for media processing and async task orchestration. https://vareyko.com/projects/bolimond Interviewer App Interview-preparation platform storing structured interview Q&A with a MySQL-backed relational model, real-time features over WebSocket, and server-rendered admin views via Thymeleaf. README notes a premium/paid-content angle for certain question sets. https://vareyko.com/projects/interviewer-app Own Reposilite A personal Maven repository powered by Reposilite. Most of the packages publicly available, but hidden. https://vareyko.com/projects/reposilite Own Verdaccio A personal npm repository powered by Verdaccio. Contains mostly conceptual libraries, that not recommended to be used standalone https://vareyko.com/projects/verdaccio Smart Backups Smart Backups is a self-hosted backup cloud: applications publish their backups through secure single-use links, and a coordinating server schedules delivery to private storage with configurable retention policies. Files travel directly between the application and the storage host — bypassing the cloud — with integrity verification, resumable transfers and optional encryption whose key never leaves the application. Restoring takes one click in the web admin: the storage pushes the requested copy straight back to the application. https://vareyko.com/projects/smart-backups Bombuilder BY A playful one-page gamer profile with a full custom admin panel. Platform links (Steam, Discord, Epic Games, GOG and 17 more), bio, PC specs and favorite games are all managed from the admin UI and stored in MongoDB — no redeploys for content changes. Built-in privacy-friendly analytics (hashed IPs, GeoIP country breakdown, bot filtering) with a live visitor counter on the page. Interactive canvas dot-grid, crosshair cursor with shot particles and an FPS watchdog that auto-degrades effects on weak devices. https://vareyko.com/projects/bombuilder

Commercial Projects https://vareyko.com/commercial

Beauty Studio "Krasa" App Application for a Beauty Studio. Server application with an admin panel where schedules, integrations, payments, etc. can be managed. Client apps for Android & iOS published on Google Play and the App Store. Own page with links to download can be found here: http://drybar.by/ A system with a flexible architecture, it has integrations with a bunch of APIs, such as 1C, a bank API, Firebase, etc. Optimized for work on a slow network, it has its own high-performance cache implementation and detects internal and UI errors and performance issues. The admin panel provides the ability to configure almost everything and check the application's state in real time. https://vareyko.com/commercial/drybar Tower Management Portal Application for management of existing communication towers and a tool for modeling antennas/equipment/cables and other devices. The most interesting part here for me was the development of the 3D Editor, which would work fast and be stable on any device, provide the ability to support most of the modeling formats, and build AutoCAD drawings. https://vareyko.com/commercial/tower-management TouchCommerce TouchCommerce a US-based enterprise customer engagement and e-commerce conversion platform. The platform combined live chat, guided self-service, personalization, customer analytics, and automated engagement tools to help large brands improve online sales, customer experience, and support efficiency. https://vareyko.com/commercial/touch-commerce Vdan A porfolio of renovation/construction company in Minsk, operating since 2006. Large project portfolio (apartments, houses, commercial and office spaces) and client testimonials emphasizing on-time delivery and transparent estimates. https://vareyko.com/commercial/vdan MDHS Program Integrity — SNAP Fraud Case Management System Client: Mississippi Department of Human Services, built by NSPARC (Mississippi State University). Role: lead backend developer, Dec 2016 – Mar 2018. What it does: end-to-end workflow for SNAP fraud investigators: fraud tip intake, EBT transaction search and pattern marking, FNS permission requests, DPI forms, claims with charge and determination letters, administrative hearings with waivers and audio, household and retailer profiles with transaction histograms, notes, tags and a full audit log. https://vareyko.com/commercial/snap-integrity Iotatech Claims (CLM) — cloud-native SaaS platform for insurance claims management A multi-tenant, pay-per-use claims management system for insurers and third-party administrators. Insurers configure their own product lines, data models, FNOL (first notice of loss) forms and rules in a configuration portal; claim handlers work claims, tasks, documents and claimant communication (e-mail, SMS) in a claims portal; Iotatech manages tenants in an admin portal. Each tenant gets isolated databases per service, and tenants are resolved from the subdomain. Tech stack: Backend: Kotlin, Java 8, Spring Boot, Spring Cloud Netflix (Eureka, Zuul, Config Server, Hystrix, Feign), Spring Security OAuth2/JWT, Spring Session, Hibernate/JPA with PostgreSQL JSONB, Hibernate Envers (audit trail), Hibernate Search + Elasticsearch, Liquibase, Redis, Quartz, WebSocket/STOMP, Twilio SMS, Gmail API, AWS S3, iText + Thymeleaf (PDF generation), Swagger, Gradle, Detekt, Checkstyle, SonarQube, JaCoCo Frontend: Angular 6, TypeScript, RxJS, Angular Material/CDK, ngx-translate (EN/DE), SockJS/STOMP, a shared UI library published as a private npm package, TSLint Infrastructure: AWS (ECS, ECR, S3, RDS, ElastiCache, Route53), Docker, nginx, Bitbucket Pipelines CI/CD, Git Flow, Jira/Confluence/Zeplin Architecture: 6 microservices (admin, user management, configuration, claims, change management, task management) behind an API gateway with service discovery and a centralised config server; 3 Angular single-page portals sharing one component library; per-tenant database provisioning; websocket push for live updates. https://vareyko.com/commercial/iotatech-claims-clm AMS — Automated Merchant Setup (Wirecard) AMS (Automated Merchant Setup) is the merchant-onboarding automation platform of a European payment provider. A partner submits a merchant registration through a REST API; AMS validates it against a configurable business-rule engine and provisions the merchant across around twenty downstream systems — acquiring and processing platforms, risk and terminal configuration, ticketing, notifications and alternative payment methods (Alipay, Apple Pay, Klarna, Sofort, WeChat Pay, Paylib, Zapp) — through a versioned, resumable workflow graph. The platform is a 41-module Maven codebase (~260k lines of Java, an integration module per external system) deployed as an RPM-packaged Tomcat application with an Oracle database. Main features: REST registration API with an XSD contract and partner templates; rule-based validation with environment-specific rule sets; a workflow engine that builds a dependency graph of provisioning nodes per registration, tracks versions and resumes from the failed node; adapters to the external systems with health checks; an operations portal with registration search and filters, node and data-flow views, request/response payload viewer, per-system performance breakdown, partner/user/operator administration; notifications by e-mail, OTRS tickets and partner callbacks; scheduled jobs for 3-D Secure enrolment, GDPR clean-up and reporting. https://vareyko.com/commercial/automated-merchant-setup Blog Writer Blog Writer is a self-hosted AI pipeline that keeps a company's blog alive from the content the company already produces: the videos and photos it posts about its work. What it does Watches the company's Telegram and Instagram and fetches every new post whole: videos, photos, caption. Analyses the video: a model watches the whole clip and extracts the car, the service, the before/after numbers and the best moments for frames. Writes a full SEO article to a contract: title, meta, structure, FAQ, internal links to the company's service pages. Checks it: a programmatic SEO check plus a critic model that verifies facts against the source, technical consistency and overlap with what is already published. Waits for a person: approve, edit, comment, replace a picture or reject; nothing goes live without approval unless AUTO mode is on. Publishes into the site's CMS on a schedule, with cross-links from older articles and a sitemap refresh. Proposes new topics from what people actually search for and from clusters of finished jobs, researches them and writes them citing only the company's relevant cases. Killer features Articles built on real footage and real measurements, not generic text. Pictures from the company's own video: scored frames, a chosen hero, the post's photos placed in the article, one-click redraw of any picture with a description in any language. Operator comments are binding: the critic verifies that every comment was honoured before the article comes back. Any model in any role: cloud providers or a self-hosted model behind an OpenAI-compatible endpoint, switched in settings without code changes. A paced queue: an hourly budget and a ready-articles buffer let a backlog of hundreds of old posts drain under the publication schedule instead of flooding the reviewer or the shared model. Integrations Sources: Telegram (TDLib reader), Instagram Graph API, manual upload. CMS: Bitrix through a one-file PHP bridge (publish, update, deactivate, image cleanup, sitemap). Models: Anthropic Claude, OpenAI, Google Gemini, any OpenAI-compatible endpoint. Search demand: Google Search Console, Yandex Webmaster, Yandex Wordstat, Google and Yandex suggestions. Off-site backups server for nightly encrypted archives. Also built in A bilingual admin panel (English and Russian) with beginner guides for every credential. Encrypted secrets managed in the UI, nightly encrypted backups with one-click restore, storage limits with article archiving and restoration, per-article cost tracking, background operations with progress. Start year: 2026 End year: 2026 Technologies: Java 21, Spring Boot 4.1, MongoDB, Thymeleaf, htmx, Anthropic API, OpenAI API, Google Gemini API, OpenAI-compatible home model, TDLib, Instagram Graph API, ffmpeg, ImageMagick, Bitrix, PHP, Google Search Console API, Yandex Webmaster API, nginx, systemd, Playwright https://vareyko.com/commercial/blog-writer Root Studio — Low-code Platform for a Multi-tenant Lending CRM Low-code studio and integration backend for a fintech lending CRM. Business users build CRM pages and data-entry forms in a visual editor, bind them to live data, and manage who can see what. Covers the deal pipeline, fees, contacts, tasks and notes. Microservices on the backend connect banking, crypto, FX and CRM providers. https://vareyko.com/commercial/root-studio

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