- Designed and implemented batch processing for Twitch and Kick chat messages, using Redis as a buffer and BullMQ workers for batch database operations, improving database write performance by 30% (measured via Sentry).

- Integrated Infobip for sending SMS/Viber notifications, and masking phone calls between drivers and customers to ensure confidentiality on the taxi app.

- Developed a DocuSign–Middesk proxy integration service, including a custom API manifest and automated document-signing pipeline.

- I mplemented platform-wide security improvements, including RBAC, rate limiting, idempotency, secure session management, and webhook verification.

- Developed the admin panel backend API for an AI-powered meeting CRM.

- Separated shared service logic and validation rules between user and admin roles via guards and controllers.

- Mentored junior developers, gradually moving from step-by-step guidance to independent problem solving and technical decision-making.