Experience

Lead engineer on a customer dashboard and an internal admin panel for a crypto company, in a Next.js and tRPC monorepo, from product features to data layer, security and delivery pipeline.

• Designed the widgets architecture behind both apps: self-contained tabs, imperative modals and filterable data tables, shared through internal packages.
• Built customer-facing account, access management and reporting features end to end, including scheduled and custom reports with CSV and Excel exports.
• Rebuilt an analytics data layer on BigQuery with typed queries and tiered caching.
• Strengthened authorization across a multi-tenant tRPC backend, with violation monitoring in Sentry.
• Cut build times by over 4x by migrating from pnpm to Bun and optimizing Docker builds on Google Cloud; automated release and dependency-update pull requests gated on CI.
• Cut monorepo typechecks to about 3 seconds by moving to TypeScript 7 (tsgo), oxlint and oxfmt, porting the custom guardrail lint rules 1:1.
• Built a Promptfoo evaluation harness for the team's Claude Code setup and used it to A/B test agent configurations: 3-4x faster execution and over 50% fewer turns with no loss in accuracy.
• Added structured logging, Sentry and a Playwright end-to-end suite.

• TypeScript
• Next.js
• tRPC
• Drizzle
• Postgres
• BigQuery
• Bun
• Agentic workflows

Founder

Localesy · Poland

Founded and built Localesy, a translation management product for fast-moving teams that syncs translations across projects and codebases and automates localization.

• Designed and built the whole product: translation sync across projects and codebases, and localization automation that lets teams ship in minutes.
• Built the web app on React Router, tRPC, Drizzle and Postgres, and the Next.js landing page and docs site.
• Shipped a GitHub App that reads locale files from repositories and opens pull requests with translation updates.
• Designed a type-safe diff engine with three-way merge for reviewing and reconciling translation changes.
• Built the AI translation engine with organization-level glossaries inferred from the customer's codebase, with quality assessment and proposed suggestions for low-quality entries.
• Built a translation quality benchmark suite: any model, input set and prompt through the production pipeline, MQM assessment by two LLM judges, and significance tests behind a provider leaderboard.
• Built internal tooling: a competitor capability matrix across localization platforms, a prompt simulator for the translation pipeline, and an observability layer.
• Shipped Stripe billing with Free, Pro and Max plans on a credit model, and moved background jobs from SST to Trigger.dev.
• Published the Localesy CLI on npm (TypeScript, Bun) to push, pull and translate locale files from the terminal and CI; its local analyzer sends only metadata.
• Automated npm releases with OIDC publishing, covered the app and CLI with Playwright end-to-end tests in CI, and wired Sentry and PostHog for monitoring and product metrics.

• Localization
• AI
• Agentic workflows
• TypeScript
• React Router
• tRPC
• Drizzle
• Postgres
• Next.js

Team Lead, Mentor and Expert React Native Developer

Callstack

Worked with enterprise and unicorn companies on cross-platform solutions with high traffic and business impact.

• Led teams delivering React Native and Expo apps for enterprise and unicorn clients, and mentored the developers on them.
• Led a team bringing native-like list performance to a sports betting unicorn's brownfield React Native app, with a long run of performance and code quality improvements.
• Led a performance and code quality audit for a client that produced 60+ actionable items with measurable impact, then delivered the improvements.
• Built a shared cross-platform component library and a long-term refactoring strategy, and automated development processes to speed up delivery.
• Hosted knowledge-sharing workshops for clients, including Redux Toolkit for one team, and set up the internal knowledge-sharing space.
• Contributed to open source, including 15 merged pull requests to React Native Paper: Material You theming and the Docusaurus docs migration.

• React Native
• Expo
• Next.js
• TypeScript

Full Stack Engineer

Selleo · Bielsko-Biała, Poland

Full-stack work at a web and mobile software house that serves start-ups and SMEs in Europe, North America and Australia.

• RESTful APIs and integrations.
• Validation, automation and verification solutions.
• Translated business needs into application development.
• Compliance and risk assessment.
• User experience work and automated application tests.

• Ember.js
• Elixir
• React
• Next.js

Web solutions for freelance clients, from API to interface.

• Laravel RESTful APIs and web solutions.
• UX and UI development.
• Cloud solutions with AWS and Firebase.
• Database management.

• React
• Laravel
• AWS
• Firebase