Mateusz Bagiński

Software Engineer

Ship better software, faster—without risking data integrity.

Senior software engineer & consultant helping teams modernize codebases, migrate databases safely, and launch AI‑powered apps.

Available for project, sprint, or fractional engagements.

Tooling & Stack

Languages: Python · Rust · TypeScript/JavaScript
Cloud: AWS · Azure · GCP
Data: PostgreSQL · MySQL · SQLite · Redis · dbt · Airflow
Testing: pytest · Playwright/Cypress · Locust/k6 · GitHub Actions
Low/No‑Code: Retool · Bubble · OutSystems · Airtable · Zapier · Webflow
Enterprise: Microsoft 365 (Teams/Outlook/Excel/SharePoint/Power Platform) · Slack · Jira · Confluence · Notion

Database Optimization & Migration

  • Audit current architecture and remove redundancy
  • Ensure referential integrity and correct foreign keys
  • Migrate to the right engine (e.g., MySQL → PostgreSQL) with rollback plans
  • Author robust, idempotent migration scripts with validation checks
  • Comprehensive database audits identifying structural inefficiencies

Contact me if you want: faster queries, fewer data anomalies, safer releases.

Example outcomes:

  • At AISafety.Info, I inherited a fragmented codebase with inconsistent patterns. I refactored the core architecture to establish clean separation of concerns and unified coding standards. I also migrated the scattered wiki of questions and answers to Google Docs for a centralized, searchable knowledge base.
  • At Swarmcheck, I migrated an extensive graph argumentation database.
  • I can normalize a legacy MySQL schema during migration to Postgres; split a monolith DB into service‑scoped stores; restructure an e‑commerce catalog to enable new product logic—with zero data loss.

Custom Software Development

I architect solutions matching your technical requirements and business constraints.

  • Full-stack development across Python, Rust, and TypeScript ecosystems.
  • AI-powered applications (LLMs, RAG, Knowledge Graphs)
  • High-performance systems requiring Rust's memory safety
  • Enterprise-grade web applications in TypeScript
  • Web apps, APIs, data pipelines, and automation

Low‑Code & No‑Code Solutions

  • Low‑code: Retool, Bubble, OutSystems for custom UIs & workflows
  • No‑code: Airtable (data + UI), Zapier (automation), Webflow (content)
  • Perfect for CRUD dashboards, approvals, customer portals, and cross‑tool automations

AI‑Powered Applications

  • Large Language Models (LLMs), Retrieval‑Augmented Generation (RAG)
  • Knowledge graphs; semantic search across your documents
  • Chatbots that answer with citations and guardrails

Code Refactoring & Modernization

Ship fixes and make the code feel like one coherent team wrote it.

  • Apply modern patterns; modularize long functions
  • Standardize naming and structure across the repo
  • Update and update documentation to match the reality of the code
  • Ensure type integrity to minimize the risk of runtime errors
  • Identify performance bottlenecks and security risks

Testing & Quality Assurance

Prevent degradation of performance before it reaches customers.

  • Unit, integration, end‑to‑end, performance, and regression suites
  • Coverage where it matters most (revenue paths, compliance, data safety)

Examples of business-specific services:

  • E‑commerce: edge‑case checkouts (expired cards, mid‑purchase inventory updates, tax jurisdictions)
  • Finance: calculation accuracy, transaction atomicity, strict access control
  • Healthcare: permissioned record retrieval, HIPAA‑style data handling, scheduling conflicts
  • SaaS: multi‑tenant isolation, accurate analytics, large‑volume exports

Enterprise Integration

Connect your stack to the tools your teams already use.

  • Microsoft: Teams, Outlook, Excel, OneDrive, SharePoint, Power Platform
  • Collab: Slack, Notion, Confluence, Jira
  • Cloud: AWS, Azure, Google Cloud
  • Legacy: Custom APIs, internal databases, intranet apps

Contact me if you want: to automatically generate Excel/PowerPoint from live data; Slack alerts on app events; CRM ↔ internal tool sync; modern wrappers for systems without APIs.