Portfolio

As a full-stack developer in a large team I owned much of the customer dashboard and several back-end services:

• Lead distribution: round-robin, weighted, team and hybrid strategies with manager availability and calendars; a drag-and-drop manual order.
• Calendars and booking: Google Calendar and Calendly with webhooks, two-way sync, a free-slot service across all calendars, protection against double booking, booking exposed to the AI agent through function calling.
• AI agent: function calls for slots, booking and contact updates; knowledge-base search with incremental indexing; language switching with confirmation; six conversation styles; guardrails against prompt injection; token checks before every model call.
• Flow builder: a redesigned visual editor with variables, validated edges and auto-layout, autosave and rollback, and a migration of all flows from JSON to relational tables without data loss.
• Channels: one configurator for voice, email, SMS and iMessage with real-time validation and a channel-integrations page.
• Telephony: call history, recordings and transcripts, voice settings for several speech providers, call campaigns from CSV, browser test calls, a move to streaming speech recognition, and a SIP bridge with two carriers — including a race condition between carrier events and SIP signalling that I tracked down and fixed.
• Token billing: a balance dashboard with forecast, Stripe pay-as-you-go, subscriptions, auto top-up and invoices, live balance over WebSocket, plan limits and discounts all the way to Stripe, unlimited owner roles synced between two databases.
• Phone-number marketplace: number search and purchase priced in tokens, regulatory verification by country, spending reports, audit log and roles.
• Security: two-factor login including after OAuth, SAML SSO, service-to-service JWT, PII masking.
• DevOps: Dockerfiles for every service, migration of production from AWS to Azure with infrastructure as code, runbooks and an atomic switch of 13 DNS records; PgBouncer for 12 Python services after connection-pool exhaustion.
• Quality: about 25,000 lines of tests (PHPUnit, Vitest, pytest, E2E).

I owned the notification microservice and its front end: one template system for email, SMS and Telegram, delivery logs with full content, read status, per-channel delivery settings (moved from primary/backup to multi-select), a Telegram bot; service-to-service authentication with a token client cached in memory and Redis and a move to JWT-only without stopping other services; integration with the government tax-data service — tax-ID lookup, digital-signature expiry checks and tax-payment analytics with risk scoring; a notifications page and bell in the web app; tests and deployment guides.

My main area was the rich-text and Markdown editor:

• Code blocks on CodeMirror 6 inside the editor: two-way sync of changes and selection, line numbers, syntax highlighting, undo and redo, leaving the block with arrow keys, correct copy and paste.
• Editing: a Markdown source mode remembered per user, input rules for emphasis and strikethrough, a simplified toolbar with new icons and H1–H4, a collapsible menu that remembers its state, links from selected text, relative URLs and heading anchors, emoji search with translatable keywords.
• Keyboard and accessibility: Tab works in lists, tables and code and moves focus elsewhere, Tab in the last table cell adds a row, an accessible menu with keyboard focus.
• Quality and delivery: 18 broken tests fixed and new ones added, dependency upgrades, ESLint, a smaller bundle, a Rollup config, CI and automatic npm publishing by tag, eight releases of the editor package.
• Platform: an onboarding tour for new users, soft deletion of users with their linked logins, configurable collapsed-post height, unread-message indicator, invite fixes, the start of a Bootstrap 5 migration, an enterprise theme, calendar, push notifications and content moderation.

I made it bilingual (English and Ukrainian) without rewriting the theme: templates switched to the current language, and all custom-field labels and product texts registered for translation in code. Later I added an “About” page with an interactive export map of 59 countries for desktop and mobile, bilingual anti-fraud disclaimers with pop-ups, and fixes to the home page. In 2026 I audited the platform and prepared a scoped plan for its next stage: content refresh, a new brand page, technical specifications for products, a reviews section, and an Arabic version with right-to-left layouts.

Over a short engagement I built real-time notifications over sockets (unread state, match and league invitations, new-subscriber events on the back end), user management for admins (roles, ban status with a reason, search and sorting, a guard against changing your own role), payment management with blockchain and account transactions, and a categories admin with image cropping and a separate game-rules module in the API.

For a year and a half I was one of the most active front-end developers and also reviewed and merged other developers’ work:

• Chat and threads: a rich-text editor with mentions, emoji, pasted images and drag-and-drop files; voice messages that work across browser, desktop and iOS; threads with badges, pagination and deep links from push notifications; infinite scroll with “jump to present”; search; group chats and DMs; turning a message into a task, event or note with its attachments.
• Boards and tasks: kanban with drag-and-drop and auto-scroll, backlog and archive, labels and filters, estimates, subtasks, personal boards updated in real time.
• Calendar, notes and files: reminders, all-day and recurring events, daylight-saving handling, checklists, a data room with public and private folders and permissions.
• Video calls: calls in spaces, projects and DMs, a ringtone that works in the background on iOS, external guests.
• Mobile and desktop: new navigation and redesigned screens, iPad and landscape support, Android and iOS builds and store accounts, desktop notifications, Do Not Disturb, deep links and signed builds for Windows and macOS.
• Performance: key lists moved to NGXS state, thread caching, an Angular and TypeScript upgrade.

• Analytics for a SaaS platform · 2021. Google Analytics data parsed and structured into dashboards and charts for the platform’s customers. Angular, Node.js, Express, MongoDB.
• Furniture online store · 2018–2020. Product-card changes, shipping and payment integrations, custom modules on OpenCart. PHP, JavaScript, MySQL.
• Stock-photo marketplace for photographers · 2016–2020. Photo upload and download, metadata extraction, filtered search, payment systems and file storage on AWS S3. PHP, JavaScript, MySQL, AWS.
• IoT monitoring of network devices · 2017–2020. Commands to custom routers over MQTT, data collection from remote devices, dashboards and user alerts when analysis hits set conditions. Angular, Node.js, Express, MongoDB, PHP, Shell.
• Guitar-learning app for iOS and Android · 2017. Video lessons, favourites and push notifications about new lessons. Ionic, Angular, REST API.
• Habit-building app for iOS and Android · 2016–2017. Built from scratch: daily tasks and mood, a calendar, achievement charts, scheduled local reminders. Ionic, Angular.
• Bluetooth device control app · 2015–2016. Finding devices, password-protected pairing, sending BLE commands and showing their status, logging and error handling; published in the App Store and Google Play, with a WordPress landing page. Ionic, Angular, Cordova, WordPress.