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Mateusz
Pachulski

🇳🇱 Dutch fluent · EU timezone · Remote

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7+ years 4 countries 3 industries 6+ apps shipped

Selected Work

40+

Santander / Erste Bank

Large-scale banking rebranding and multi-country app migration. Identified and resolved 40+ UI regressions across 4 countries before reaching production.

Rebranding WCAG CI/CD Kotlin Jetpack Compose
100%

Wire Messenger

Full app rewrite from scratch using Jetpack Compose + KMP. Built the shared business logic layer covering networking, data persistence, and domain models across Android and iOS — serving millions of users with zero downtime during the entire migration. KMP was central to architecture decisions from day one.

Jetpack Compose KMP gRPC E2E Encryption SQLDelight
4mo

FitCrony

Sole developer from concept to Google Play in 4 months. Full Flutter fitness app — architecture, UI, and release management solo.

Flutter Dart Health MVP Google Play

What I Do

Banking apps, encrypted messengers, IoT SDKs, trading platforms. I’ve shipped them all — here’s what I can do for yours.

  1. Android Development

    Kotlin and Jetpack Compose done right — clean architecture, proper test coverage, and no hacks that haunt you six months later.

    KotlinJetpack ComposeClean ArchitectureCoroutines
  2. Kotlin Multiplatform

    One shared business logic layer across Android, iOS, and server. I’m also building with on-device ML — it’s where things are heading and I want to be ahead of it.

    KMPKtorSQLDelightOn-device ML
  3. Architecture Consulting

    ADR-backed architecture proposals, module boundaries, and Gradle optimisation. From monorepo setups to multi-country banking platforms.

    ADRMonorepoGradleMVI
  4. Real-Time Data & FinTech Apps

    Crypto trading platforms with live WebSocket data visualisation. Multi-country core banking modules used daily by millions of users.

    WebSocketsRxJavaBankingReal-time

How I Work

No surprises, no scope creep. Here’s exactly what working together looks like — from first call to shipped product.

  1. Discovery Call

    30 minutes to understand your problem, goals, and constraints. We align on scope before a single line of code is written.

  2. Proposal & Architecture

    I write down what we’re building, how, and when — just enough to move with confidence. No 40-page documents, just a clear plan we both agree on before anything starts.

  3. Sprint-Based Delivery

    You get a weekly update and something you can actually test. Real progress, not slide decks. AI tooling helps me ship faster without cutting corners on quality.

  4. Ship & Handover

    CI/CD set up, docs written, and I walk your team through what was built. You own it from day one — not just the files, but the understanding of why things are the way they are.

  5. Post-Launch Support

    Optional retainer or bug-fix period. I stay reachable after delivery — not just until the invoice clears.

My Stack

7 years building real things. Banking apps across 4 countries, an encrypted messenger for millions, a BLE mesh SDK from scratch — the stack reflects the work.

Android

KotlinJetpack ComposeAndroid SDK Clean ArchitectureMVICoroutines Dependency InjectionJavaReactive Programming

Platform & Connectivity

Kotlin MultiplatformKtorSQLDelight KoinProtobufgRPC BLEEncryption

Tooling & Quality

Snapshot TestingWCAG / Accessibility ADRGradleCI/CDOn-device ML

Languages

Dutch (fluent) English (professional) Polish (native)

AI & Agents

LLM APIsAI AgentsPrompt Engineering CursorCopilot

Timeline

* f9e0a1b (HEAD → main) Exploring AI & Agent-driven Development [2025–Present]

Building side projects with AI agents — LLM APIs, Cursor, agentic workflows. Figuring out what actually changes when the tools get this good. Spoiler: quite a lot.

* a1b2c3d (origin/santander) Senior Android Developer @ Santander / Erste [2023–2025]

Hired into the core team delivering features across 4 countries; 30+ XML → Compose migrations, WCAG accessibility rollout, monorepo Gradle alignment, introduced ADRs. Acted as bridge between the Polish business unit and Santander Digital Services. Later led the Poland mono repo migration and the full rebranding to Erste following the acquisition.

* d4e5f6b (origin/wire) Senior Android Developer @ Wire Messenger [2021–2023]

Built Wire Messenger from scratch with Jetpack Compose — end-to-end architecture decisions, daily collaboration with designers on product direction, E2E-encrypted features over gRPC, and shared business logic via KMP (Ktor / Koin / SQLDelight).

* g7h8i9c (origin/appunite) Senior Android Developer @ AppUnite [2019–2021]

Multi-client Android delivery: AlleFolders Dutch brochure-browsing app (bug fixes & features), BlockTrade crypto platform with live prices and real-time graphs (RxJava, reactive programming), multiple radio app releases, and FitCrony fitness app built solo in Flutter.

* j0k1l2d (origin/bright) Android SDK Engineer @ Bright Inventions, Gdańsk [2017–2019]

Built a BLE-mesh Android SDK as sole engineer — replicating the iOS implementation through unit tests with full documentation. The SDK powered a BLE mesh where dedicated devices exchanged data with phones acting as radars for BLE signals. Ran in parallel with a companion pet-tracking demo app.

* n3o4p5e (origin/edu) B.Eng Electrical & Electronics @ Hanze University, Groningen [2014–2019]

Electrical & Electronics Engineering — foundation in embedded systems, signal processing, and hardware-software integration. Originally from Poland; studied and lived in the Netherlands for 14 years.

Let’s Work Together

Have an Android project, a codebase that needs rescuing, or a startup idea that needs an app? Tell me about it.

Currently available — responses within 24 hours