Running Cat Development
Independent software studio · Katowice, PolandAvailable for new projects

App development. Done well, delivered fast.

I develop mobile apps for startups and businesses: Android, Flutter and Kotlin Multiplatform. I help founders with mobile teams, architecture and release processes. For MVPs and prototypes, I can also build the web part and the backend.

  • 9+ years in mobile
  • Android · Flutter · KMP
  • SaaS · AI products
  • Apps used by millions
Services

How I can help

Choose one format or combine several.

  1. 01

    Mobile development

    Android apps in Kotlin and Jetpack Compose, cross-platform apps in Flutter and Kotlin Multiplatform. Full cycle: architecture, development, testing and release to the stores.

    • New apps and MVPs
    • Features for existing apps
    • AI features, subscriptions, A/B tests
    • Migration to KMP or Flutter
  2. 02

    Mobile lead for founders

    A part-time technical lead for your mobile product. I help choose the stack, design the architecture, hire and onboard developers and set up a stable release process.

    • Architecture and technical decisions
    • Hiring and onboarding
    • Code review, CI/CD, releases
  3. 03

    App audit

    A review of code, architecture, stability and performance. You get a prioritised list of issues and a plan to fix them. If needed, I fix the critical ones myself.

    • Code and architecture review
    • Stability and performance
    • Technical debt plan
  4. 04

    MVP and prototypes

    When you need to test an idea quickly, I can build a simple web app, API or admin panel for an MVP or prototype. Fast, with modern AI tools.

    • Web MVPs and prototypes
    • Simple APIs and integrations
    • Admin panels
Projects

Selected projects

Products I have built or worked on.

Cycling SaaSTrainCrafttraincraft.app

Founder & engineer

Cycling training platform with AI: workouts, adaptive plans, route analysis and race predictions. Web app plus mobile apps built with Kotlin Multiplatform.

  • Kotlin Multiplatform
  • Web
  • AI
AI CAD toolPurCadpurcad.app

Founder & engineer

AI CAD for functional 3D-printable parts: from a text or a photo to an editable, validated model.

  • AI
  • CAD
  • Web
Air quality appAtmiqatmiq.xyz

Founder & engineer

A web service and an iOS and Android app that help you understand whether the air is suitable for outdoor training, taking the kids out or opening the windows right now — and when it will be. An air quality map, a 48-hour forecast and alerts when conditions change.

  • Kotlin Multiplatform
  • Compose Multiplatform
  • Next.js
Cry & mood trackerSaltwatersaltwater.runningcat.dev

Founder & engineer

A crying journal and mood tracker for iOS and Android. Helps you understand what moves you and what brings relief, with a live crying timer, personal insights and hugs from friends.

  • Kotlin Multiplatform
  • Compose Multiplatform
  • iOS
  • Android
Mac energy managementWattGuardwattguard.runningcat.dev

Founder & engineer

Energy management for macOS: process diagnostics, sleep and wake analysis, battery health and power modes. Automates Wi-Fi, Bluetooth, apps and Shortcuts based on schedules, sleep state and power conditions.

  • Swift
  • SwiftUI
  • macOS
Route stops & planningpoipoi.runningcat.dev

Founder & engineer

An iOS and Android app for finding water, food, sights and places to stay along a route. Import a track or build your own, add stops, then export a GPX to your preferred app or device for a hike, bike ride or trip.

  • Kotlin Multiplatform
  • Compose Multiplatform
  • TypeScript
Geo & weather APIRunning Cat Geo APIgeo.runningcat.dev

Founder & engineer

An OpenStreetMap API for developers. Overpass-style queries, weather forecasts, air quality, river levels, elevation and routing for bike, hiking and car, all with one key. Includes an MCP server for AI assistants.

  • TypeScript
  • OpenStreetMap
  • MCP
Consumer AI appBlushblush.ai

Mobile Technical Lead

AI dating simulator. Built the Flutter app from the first commit and led it on Android, iOS and web through 45+ releases.

  • Flutter
  • Android
  • iOS
  • Web
Consumer AI appReplikareplika.com

Senior Android Engineer

AI companion app used by tens of millions of people. Brought Jetpack Compose to production and cut app load time by about 20%.

  • Android
  • Kotlin
  • Compose

Replika and Blush are trademarks of their respective owners.

How I work

Engineering approach

Regular results

Short iterations and a working build every week, so progress is always visible.

Quality control

Tests, CI and release checks from the first day. Crash rate and store ratings are tracked as product metrics.

Clear terms

Fixed scope or a monthly rate, clear estimates. All code and accounts belong to you from the start.

AI-assisted workflow

Modern AI tools speed up research, prototyping and routine code. Architecture, review and tests keep the result solid.

Technologies
  • Kotlin
  • Jetpack Compose
  • Kotlin Multiplatform
  • Flutter
  • Android
  • iOS
  • TypeScript
  • Next.js
  • LLM integrations
  • CI/CD
Contact

Tell me about your project

A few sentences are enough: what you are building, what stage it is at and what you need help with.

Or write directly:

I usually reply within one working day.
English · Polski · Русский

Topic