• Significant changes of a lot of processes: Identified and eliminated operational bottlenecks across the product lifecycle, pushing for systemic changes rather than just local fixes.

• Self-Hosted Payment Service: implemented a centralized payment service that reduced failed transactions and data inconsistency, while handling multiple providers, 3DS/OTP flows, and backward compatibility with legacy flows.

• Client-Side A/B Testing: created tools that let product teams launch experiments without developers, solving challenges around correct user assignment, metric collection, and minimal performance impact.

• No-Code Page Builders: tools that allow non-technical teams to create different types of interactive flows and deploy complex funnels in hours instead of days, removing engineering bottlenecks from campaign launches.

• Next.js App Router Migration: led the migration from legacy pages to a new app architecture with standalone builds, improving UX and maintainability while preserving SEO, analytics, and user behavior with zero downtime.

• E2E Health Checks: architected Playwright-based tests for critical [nflows that run in production directly against internal Kubernetes services, bypassing public networks to ensure product stability and detect invisible malfunctions.

• Advanced Observability (RUM): integrated Grafana Faro to capture real-time Web Vitals and API errors without affecting main-thread performance, enabling data-driven optimization of user retention.

• AI-Driven Features: implemented AI-powered [NDA], increasing user engagement and session duration through interactive content.

• Global Privacy Compliance: developed geo-segmented compliance logic (GDPR, CCPA, etc.) to stay compliant with privacy regulations while preserving useful analytics, dealing with complex consent logic and many tracking scripts/pixels.

• Cloud-Based i18n Architecture: moved translations to AWS S3 with automated cache invalidation, reducing the main bundle size and allowing instant content updates without application redeployment.

• Proactive Error Monitoring: configured custom Sentry tagging for business-critical flows, filtering noise to focus on high-priority incidents and significantly reducing mean time to resolution (MTTR).

• conducted 100+ interviews with Front-end developers

• transferred a project with 20 mirrors and a multi-entry structure from CRA + rewired to Vite

• develop interactive games for contests

• implement feature-toggling

• implement payment cascade

• rewrote CRM from yii2 on Next.js 14

• implement GrowthBook

• implement thematic events, holiday themes

• transition from NodeJS to Fastify/NexusJS

• transition from Fela to MUI; SWC tree shaking optimization

• implement SSE instead webhooks

• transition from Recoil to contexts and React Query

• optimize queries with GraphQL

• create SDK and DOM widgets for third-party platforms

• optimize HLS and big assets

Headed one of two teams (iOS/Android, fullstack developers and content managers):

• rewrote the platform from Vue/Next.js on Node/React

• implemented React 18 features (suspense, etc), RTK Query on frontend; Sentry, Prisma ORM on backend

• setup CI/CD

• developed algorithms for A/B

• test covering with jest/chai + moch

• saved colleagues’ nerve cells by putting microservices on the shoulders of AWS and Firebase

• under the direction of the team leader, refactored about a third of the legacy code from AngularJS to React, the rest was on class components and was also rewritten

• implemented emotion and chakra-UI instead of PostCSS

• completed the transition from Flow to TypeScript

• initiated the transition to Trunk-based-development

• worked with motion graphics, creating complex animated elements

• implemented React Cosmos