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Software house + AI

AI app development and AI-assisted coding – web and mobile

We build apps with artificial intelligence features and develop them with the latest AI coding tools – Claude Code, Cursor, GitHub Copilot. You get a working prototype in days and your app faster and cheaper, while the experienced 4B Systems team takes care of architecture, testing and security.

Web appsMobile appsAI agentsAI testing
Claude CodeCursorGitHub CopilotOpenAI CodexGemini CLIWindsurfv0LovableBoltPlaywrightMCPClaudeGPTGeminiMistralLlamaWhisperpgvectorLangGraph

Two ways AI works for your business

Artificial intelligence can be a feature of your app – working for your customers and employees – or the tool we build it with – cutting the time and cost of building any app, even one where AI isn't visible at all. Most often we combine both.

AI apps – AI inside the product

AI assistants and agents, document and image analysis, semantic search, summaries and forecasts. We work out which tasks are worth handing over to AI, choose the model and build the whole app around it.

AI-assisted development – every app, faster

Coding agents write code, tests and documentation under the direction of our developers. This isn't “vibe coding”: every change has a plan, a review and tests – it just takes a fraction of the time it used to.

What AI apps can we build for you?

A few examples of the projects we deliver most often. Each can be a standalone app or a module of a system you already use.

AI assistant on your company data

A chatbot that answers based on your documents, offer and knowledge base (RAG) – for customers on your website or for employees on your intranet.

AI agents in your processes

An AI agent carries out process steps on its own: qualifies leads, prepares quotes, updates the CRM, creates tasks. A human approves only what matters.

Document analysis

Reading invoices, contracts, applications and forms (OCR + language model), extracting data into your system, summaries and version comparisons.

Image recognition

Photos of shelves, products, damage or clothing recognized automatically – in a mobile app, including out in the field.

Mobile apps with AI

iOS and Android apps with AI features: camera, voice, suggestions, automatic completion of reports and forms.

AI in CRMs and dashboards

Call and email summaries, lead scoring, sales forecasts, risk detection – built into the system you already use.

Semantic search

Search “by meaning”, not by keywords – in a product catalog, technical documentation or case archive.

Voice and transcription

Speech-to-text, meeting notes, call center conversation analysis and automatic post-call reports.

AI product MVP

The first version of your product – a SaaS or mobile app – with AI at its core, ready to show to investors and your first customers.

What we build

Web apps, mobile apps and everything that connects them

We use AI-assisted development across the entire tech stack – from the front end and back end to integrations with your company systems and language models.

Web apps

Browser-based systems: customer portals, SaaS platforms, CRMs, B2B and B2C portals, online stores and marketplaces.

✓React, Vue.js, Next.js
✓PHP (Laravel), Python, Node.js
✓PostgreSQL, MySQL
✓cloud and servers in the EU
Python Web Development →

Mobile apps

iOS and Android apps for customers and field teams – with offline mode, push notifications and app store publishing.

✓Flutter, React Native
✓Kotlin, Swift
✓offline mode and sync
✓Google Play and App Store
iOS and Android mobile apps →

Back end, APIs and integrations

The heart of the app and the glue between systems: APIs, job queues, integrations with ERP, CRM, payments, KSeF (Polish national e-invoicing system) and AI models.

✓REST, GraphQL, webhooks
✓Claude, GPT, Gemini, open-source models
✓vector databases (pgvector, Qdrant)
✓automations and AI agents
ChatGPT integrations →

AI coding tools we use

We test new tools continuously and pick the right ones for each project. The same team can work with an agent in the terminal, in the editor and in the cloud – and you don't need to buy any licenses.

Anthropic

Claude Code

A coding agent in the terminal and IDE. It reads the entire repository, plans changes across many files at once, runs tests and fixes errors until they pass.

Anysphere

Cursor

A code editor with built-in AI: whole-block suggestions, chat with your project's code and an agent mode for bigger changes.

GitHub / Microsoft

GitHub Copilot

IDE suggestions, an agent that completes backlog tasks and automatic code review in pull requests.

OpenAI

OpenAI Codex

An agent for tasks in the cloud and in the terminal – several independent tasks (e.g. migrations, refactoring) can run in parallel.

Google

Gemini CLI

A terminal agent with a very large context window – useful for analyzing large legacy systems.

Cognition

Windsurf

An editor with an agent that drives multi-step changes and keeps track of the whole project's context.

Vercel / Lovable / StackBlitz

v0, Lovable, Bolt

Lightning-fast, clickable UI prototypes. We use them to validate an idea with the client – production code is written in the target architecture.

Microsoft / Anthropic

Playwright + MCP

AI writes and runs end-to-end tests in a real browser. Through MCP (Model Context Protocol), the agent has access to documentation, the test database and tasks.

In our apps we use Claude, GPT and Gemini models as well as open-source models (Llama, Mistral) – in the cloud or on your server.

Benefits of AI-assisted development

AI doesn't replace the team – it extends its reach. The same people deliver more features, better tested, in less time.

Faster start

A clickable prototype takes days, not weeks. You validate your idea with users sooner, before investing in the full version.

Lower cost of the first version

AI takes over repetitive work: forms, CRUD screens, migrations, tests, documentation. Your budget goes into what makes your product stand out.

More tests, fewer bugs

We generate unit and end-to-end tests together with the code. Every change goes through automated checks before it reaches you.

Better documentation

API descriptions, deployment instructions and comments stay up to date – making the project easier to take over and develop, even years later.

An experienced team at the helm

AI writes fast, but a developer approves the architecture, security and every code change. Accountability stays with us.

Data security

We use tools on business plans, with no model training on your code. On request, models in the EU or on your server.

AI-assisted development process – step by step

At every stage we split the work clearly: AI does what it's fastest at, while people make decisions and own the quality. We work in sprints – every two weeks you see progress in a working version.

1

Workshop and specification

We define the goals, the users and the scope of the first version.

What AI doesWorkshop transcription, user stories and acceptance criteria in a few hours.
What our team doesBusiness decisions, priorities, MVP scope.
2

UI prototype

Before the actual code is written, you click through a working prototype.

What AI doesGenerates screen variants and clickable mockups (v0, Lovable).
What our team doesUX, brand consistency, choosing the variant with you.
3

Architecture

We choose the technologies, database, integrations and AI models.

What AI doesAnalyzes alternatives, sketches diagrams and estimates model costs.
What our team doesFinal architecture, security, scaling.
4

Development in sprints

Every 2 weeks you get a working version to review.

What AI doesAn agent (Claude Code, Cursor, Copilot) writes code according to plan and runs the tests.
What our team doesTask planning, review of every change (code review), refactoring.
5

AI-assisted testing

Automated and manual testing at every stage.

What AI doesWrites unit and E2E tests, looks for edge cases, does a first-pass code review.
What our team doesCritical scenarios, acceptance testing, quality sign-off.
6

Deployment and release

We launch the app on the server and in the app stores.

What AI doesPrepares CI/CD configuration, release notes and store listings.
What our team doesProduction deployment, monitoring, handover of access.
7

Maintenance and development

The app lives on: updates, new features, support.

What AI doesAnalyzes error logs, suggests fixes and library updates.
What our team doesHelpdesk, SLA, a data-driven development roadmap.

AI in software testing

Writing code fast only makes sense if we check its quality just as fast. That's why tests are written together with the code, and every change goes through automated verification – before a human even sees it.

Unit and integration tests

AI generates tests together with the code and adds edge cases that are easy to forget.

End-to-end browser tests

User scenarios in Playwright – login, checkout, forms – run on every change.

Device testing

Different phone models, iOS and Android versions, poor signal and offline mode.

Security

Automated dependency and code scanning, permission review, testing against the OWASP Top 10.

Testing AI features (evals)

Sets of control questions check the accuracy of model answers, hallucinations and resistance to prompt injection.

Code review: AI + human

AI comments on every pull request first, and a developer approves the change. Nothing reaches production without approval.

Quality and security

AI writes, humans are accountable

The fastest code is worthless if it can't be maintained safely. That's why we follow a few simple rules:

✓Every code change is reviewed and approved by a developer – AI deploys nothing on its own.
✓We hand over the code, the design and the copyright to the client as set out in the contract.
✓AI tools on business plans, with no model training on your code and data; NDA on request.
✓Personal data handled in line with GDPR; for sensitive data, models in the EU or on your infrastructure.
✓We design AI features with the EU AI Act requirements in mind: transparency, human oversight, decision logs.
From our projects

AI in apps that work

Merchassistant (MarketEye)

A mobile app and browser-based system for managing merchandising in the FMCG industry, with surveys and image recognition technology. Used by more than 4,000 people in the field. See the app

WearMeUp.Club

A web and mobile platform for sewing enthusiasts: made-to-measure patterns and a machine learning module that recognizes clothing from photos. Read the case study

AI chatbots and assistants

Assistants on websites and in company systems, built on the client's own knowledge. AI chatbots for business

Contact us

Have an idea for an AI app? Let's validate it together

Describe in a few sentences what you want to build or which business process you want to improve. We'll call you back, ask about the details and suggest where to start – often with a clickable prototype you can show to your users.

✓We reply within one business day
✓Free consultation: what's worth handing over to AI and what isn't
✓Initial budget, timeline and architecture within 48 hours
✓NDA before we discuss the details – on request

Prefer another way? Contact details and office addresses →

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AI apps and AI-assisted development – frequently asked questions

AI apps are programs in which artificial intelligence does part of the work for the user: it answers questions, analyzes documents and images, summarizes conversations or carries out process steps on its own (AI agents). They can run as a web app, a mobile app or a module of an existing system, such as a CRM.

AI-assisted development means that tools such as Claude Code, Cursor or GitHub Copilot write and test code under a developer's direction. Vibe coding usually means generating an app without reading or understanding the code – fine for quick prototypes, but not for production systems. We combine the speed of AI with engineering: architecture, review of every change and testing.

Day to day we use Claude Code, Cursor, GitHub Copilot, OpenAI Codex and Gemini CLI, and for quick UI prototypes v0, Lovable and Bolt. We automate end-to-end tests with Playwright and connect agents to documentation and tasks via MCP (Model Context Protocol). The choice of tools depends on the project and the client's requirements.

Yes, as long as people stay in charge of the code. With us, every change goes through developer review, automated tests and a dependency security scan. AI speeds up writing code, but decisions about architecture and security are made by the team.

Usually yes – especially the first version (MVP), because AI takes over repetitive work: forms, admin panels, migrations, tests and documentation. The savings depend on the project; we give you a specific budget and timeline in our quote, which we prepare within 48 hours.

We use tools on business plans where providers do not train models on customer code and data. We sign an NDA on request, and in projects with sensitive data we use models hosted in the EU or running on your own server.

Most often Claude (Anthropic), GPT (OpenAI) and Gemini (Google) models, and when data must not leave the company – open-source models such as Llama or Mistral, run locally. We match the model to the task, the cost and the legal requirements, and design the app so the model can be swapped later.

We usually deliver a prototype you can show to users in 1–2 weeks, and the first production version (MVP) in 1–3 months, depending on the number of features and integrations. We give you an exact timeline after the workshop, together with the quote.

Yes. We often start with a single module in your existing system – e.g. an assistant in the customer portal, document analysis or summaries in your CRM – and expand it once it delivers results.