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Mateusz Rajski

PROFILE

Mateusz Rajski

Mateusz Rajski contributed to Expensify-App and its forks by delivering robust data visualization features, search enhancements, and improved localization. He developed and refined charting components, such as BarChart and LineChart, integrating them with search and ensuring accurate rendering and label layout. Using TypeScript, JavaScript, and React Native, Mateusz focused on code quality through extensive unit testing, refactoring, and configuration management. He addressed memory management, authentication reliability, and CI/CD health, while also upgrading dependencies for performance and compatibility. His work improved user experience, supported internationalization, and strengthened maintainability, demonstrating depth in frontend development and full stack engineering practices.

Overall Statistics

Feature vs Bugs

65%Features

Repository Contributions

202Total
Bugs
33
Commits
202
Features
61
Lines of code
79,245
Activity Months6

Work History

March 2026

19 Commits • 3 Features

Mar 1, 2026

March 2026 monthly summary for callstack-internal/Expensify-App focusing on delivering robust data visualization, reliable UI behavior, and lifecycle/telemetry improvements. Key outcomes include more accurate and stable chart rendering, correct reset of sort state across views, and security/telemetry enhancements that improve offline capabilities and reduce risk. Strong emphasis on test coverage and code quality to support sustainable velocity.

February 2026

58 Commits • 19 Features

Feb 1, 2026

February 2026: The expensify-app-fork repository saw a focused set of deliverables across charting UX, localization, build profiling, authentication reliability, and test coverage. Key outcomes include a robust LineChart labeling/layout overhaul, improved internationalization and currency formatting, improved Gradle profiling for faster performance insights, hardened sign-out and auth error handling, and expanded test coverage reducing regression risk. These changes collectively enhance user experience, support global customers, and improve developer productivity and code quality.

January 2026

75 Commits • 21 Features

Jan 1, 2026

January 2026 performance summary: Delivered substantial improvements to search and charting experiences across Expensify-App forks, strengthened localization, and raised testing and tooling standards. Key outcomes include view-aware search enhancements, stabilized URL handling, and robust charting components; plus enhanced localization and a broader testing infrastructure that improves reliability and developer velocity. These efforts translate into faster, more accurate data-driven decisions for users and reduced maintenance risk for the team.

November 2025

2 Commits • 1 Features

Nov 1, 2025

November 2025 — Expensify/react-native-onyx Key feature delivered: - Upgraded React Native Performance library from 2.0.0 to 5.1.0 to boost performance metrics and ensure compatibility with latest features and fixes. This included updates to dependency files (package.json and package-lock.json) to lock the new versions and support reproducible builds. Major bugs fixed: - No major bugs reported for this repo this month. Overall impact and accomplishments: - Improved performance metrics and user experience through a major library upgrade. - Enhanced stability and forward compatibility with the React Native ecosystem. - Clean dependency hygiene with explicit lockfile updates to support reproducible builds and easier maintenance. Technologies/skills demonstrated: - React Native, dependency management, npm/yarn-based workflow, version upgrades, and lockfile maintenance. Business value: - Faster, more reliable app performance across platforms, reduced risk of regressions with newer RN features, and improved telemetry for ongoing optimization.

October 2025

21 Commits • 7 Features

Oct 1, 2025

Month 2025-10 — Expensify/App: Focused on stability, observability, and release-readiness. Deliverables spanned bug fixes, CI/CD health, security hardening, and documentation/maintainability improvements with clear business value for faster, safer releases and a better developer experience. Key deliverables: - Memory leak fix in react-native-performance to restore memory usage profile and prevent leaks introduced by the patch (commit 9f0994997413bde9821ba72c7724d34f1a6c9adf). - ActivityIndicator logs revert fix to restore expected logging context and avoid confusion in observability (commit dd760b531c6a57e11e7a7b0d7b2e237134f494e0). - Documentation updates and URL corrections to reflect current state and ensure accurate onboarding and reference materials (commits 185b1f941a167ad80ba4ecd3631f8d6a00cfc1eb, 7984ecd15ad963b3343b7bd5ff079623d84cb66c, ba0da234b95d2a1b8c72359e3f06592283effc0f). - Code maintenance and clarity improvements, including removing an override and renaming a function for maintainability (commits 1af457d99ede582db289e0055b71703c4047b941, 42e0641eba64f825d1168e82240e501cdcddbdec). - CI/build system enhancements and dependency updates to improve build Verbosity, error logging, artifact handling, and CI reliability (commits: f4e0cd32a7e39bcc3ae91beff539a4b1524e3455, eea71a59e05abd2b1c69b6a78413594db4c16eea, a931f7ab6262b61b6af9bb4795fa5c673a8849d5, 20d5eafbbbff6e79140c6f5a3aebad2de9a1523d, 22381c984a9ec09de3b8716864b1c3f916f32e82, 74346434e013f391b8203db1bb3497eb1933e0de, b50d3abc130769147b5f0790b46497829a404154, 6a987ea9699d31c2d195991887c2e66dabc8cf13). - GitHub Actions authentication and validation improvements for safer workflows and proper token usage (commits 05f43bc4595707db548ebf4d0c9ea09f41592b4d, 4f85735e400122b9993fda93d19d0eb8f8df57a5, aaa7621b9c4a50702198e31346c535b7a8d3cb12). - Security-oriented cleanup to reduce attack surface by removing redundant permissions (commit 4dabf764ecead9897af2f56bbd7c22311c4928f2). - Spell-check configuration enhancements (getenv support) and Podfile updates to keep tooling aligned with the latest project setup (commits 8c22f0266b827dca5ec02e500453997044ae44ee, 382cfafe3aefd79443a83163d0db649b72d93d69).

September 2025

27 Commits • 10 Features

Sep 1, 2025

September 2025 monthly summary for Expensify/App. Delivered UI consistency, stability, and quality improvements across the mobile app, with a focus on business value and maintainability.

Activity

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Quality Metrics

Correctness94.4%
Maintainability91.2%
Architecture90.0%
Performance89.8%
AI Usage22.4%

Skills & Technologies

Programming Languages

GradleGradle PropertiesJSONJavaJavaScriptMarkdownObjective-CRubySVGShell

Technical Skills

API IntegrationAPI integrationAndroid DevelopmentAsset ManagementAuthenticationBuild AutomationBuild ConfigurationBuild ScriptingCI/CDCode CleanupCode DocumentationCode FormattingCode QualityCode StandardizationComponent Development

Repositories Contributed To

5 repos

Overview of all repositories you've contributed to across your timeline

margelo/expensify-app-fork

Jan 2026 Feb 2026
2 Months active

Languages Used

JavaScriptTypeScriptMarkdownYAML

Technical Skills

ReactReact NativeTypeScriptcharting librariesdata visualizationfront end development

callstack-internal/Expensify-App

Jan 2026 Mar 2026
2 Months active

Languages Used

JSONJavaScriptRubyShellTypeScriptproguarddotenv

Technical Skills

Dependency ManagementJavaScriptNodeReactReact NativeTypeScript

Expensify/App

Sep 2025 Oct 2025
2 Months active

Languages Used

JavaScriptSVGTypeScriptGradleGradle PropertiesJSONJavaMarkdown

Technical Skills

API IntegrationAsset ManagementAuthenticationCode CleanupCode DocumentationCode Formatting

software-mansion-labs/expensify-app-fork

Jan 2026 Jan 2026
1 Month active

Languages Used

JavaScriptTypeScript

Technical Skills

Front End DevelopmentFrontend DevelopmentReactReact NativeType SafetyTypeScript

Expensify/react-native-onyx

Nov 2025 Nov 2025
1 Month active

Languages Used

JSONJavaScript

Technical Skills

Package ManagementReact Nativedependency managementpackage management