EPPlusSoftware/EPPlus
Nov 2024 – Feb 2026
16 Months active
Languages Used
C#MarkdownPowerShellXMLYAMLymlcscsproj
Technical Skills
.NET BuildBug FixingBuild AutomationBuild ManagementCI/CDCode Refactoring
JanKallman
PROFILE
Jankallman
Jan Källman led core engineering for the EPPlusSoftware/EPPlus repository, delivering advanced Excel automation features and robust formula engine enhancements over 16 months. He architected and maintained complex backend systems in C# and .NET, focusing on formula parsing, pivot table reliability, and dynamic array support. Jan’s work included optimizing calculation performance, strengthening XML and Unicode handling, and modernizing configuration management for cross-platform compatibility. He addressed over 50 bugs and shipped more than 35 features, consistently improving data accuracy, release automation, and developer usability. His technical depth is reflected in rigorous unit testing, detailed documentation, and thoughtful refactoring across the codebase.
Overall Statistics
Feature vs Bugs
42%Features
Repository Contributions
155Total
Bugs
52
Commits
155
Features
38
Lines of code
505,219
Activity Months16
Your Network
9 peopleSame Organization
@epplussoftware.com3
Work History
February 2026
2 Commits
Feb 1, 2026February 2026 monthly summary for EPPlus: Delivered a critical bug fix and library upgrade to enhance workbook calculation stability and reliability. Key features delivered include stability improvements in formula recalculation and an upgrade to EPPlus 8.4.2. Major bugs fixed include improved handling of dependency chains to prevent stack overflow during recalculation and preventing exceptions when saving workbooks. Impact: more accurate, faster, and reliable workbook processing with fewer user-reported issues. Technologies/skills demonstrated include formula calculation optimization, dependency graph management, EPPlus version upgrade, and commit-driven changes.
2 Commits
Feb 1, 2026February 2026 monthly summary for EPPlus: Delivered a critical bug fix and library upgrade to enhance workbook calculation stability and reliability. Key features delivered include stability improvements in formula recalculation and an upgrade to EPPlus 8.4.2. Major bugs fixed include improved handling of dependency chains to prevent stack overflow during recalculation and preventing exceptions when saving workbooks. Impact: more accurate, faster, and reliable workbook processing with fewer user-reported issues. Technologies/skills demonstrated include formula calculation optimization, dependency graph management, EPPlus version upgrade, and commit-driven changes.
February 2026
January 2026
5 Commits • 2 Features
Jan 1, 2026January 2026 monthly summary for EPPlus (EPPlusSoftware/EPPlus). Focused on performance, reliability, and data integration capabilities across the core Excel processing features. Key enhancements targeted faster calculation, robust data parsing, and stronger XML handling, aligning with business goals of reliability and maintainability in file processing and automation workflows.
January 2026
5 Commits • 2 Features
Jan 1, 2026January 2026 monthly summary for EPPlus (EPPlusSoftware/EPPlus). Focused on performance, reliability, and data integration capabilities across the core Excel processing features. Key enhancements targeted faster calculation, robust data parsing, and stronger XML handling, aligning with business goals of reliability and maintainability in file processing and automation workflows.
December 2025
9 Commits • 3 Features
Dec 1, 2025December 2025: Delivered critical reliability improvements and expanded platform support for EPPlus. Focused enhancements include robust Excel formula parsing and error handling across core functions, accurate numeric detection excluding booleans with updated tests, chart handling fixes to improve initialization and series application reliability, and a stabilized internal data structure for dynamic column handling. The release of EPPlus 8.4.0 brought .NET 10 support plus targeted function fixes, significantly improving calculation correctness, chart stability, and cross-platform compatibility for customers. Demonstrated strengths include rigorous testing, commit-level traceability, and a clear emphasis on business value through reliability, performance, and platform reach.
9 Commits • 3 Features
Dec 1, 2025December 2025: Delivered critical reliability improvements and expanded platform support for EPPlus. Focused enhancements include robust Excel formula parsing and error handling across core functions, accurate numeric detection excluding booleans with updated tests, chart handling fixes to improve initialization and series application reliability, and a stabilized internal data structure for dynamic column handling. The release of EPPlus 8.4.0 brought .NET 10 support plus targeted function fixes, significantly improving calculation correctness, chart stability, and cross-platform compatibility for customers. Demonstrated strengths include rigorous testing, commit-level traceability, and a clear emphasis on business value through reliability, performance, and platform reach.
December 2025
November 2025
10 Commits • 5 Features
Nov 1, 2025November 2025 delivered targeted feature enhancements and quality improvements for EPPlusSoftware/EPPlus, focusing on data connectivity, formula reliability, and developer experience. Key outcomes include external data connections, query tables, and pivot table support (8.3.0); robustness improvements to AverageIf/SumIf with tests; XLOOKUP not-found handling improvements; Excel formula calculation fixes for calculated columns and general error handling; and the 8.3.1 release with bug fixes, performance and stability improvements, plus API documentation enhancements.
November 2025
10 Commits • 5 Features
Nov 1, 2025November 2025 delivered targeted feature enhancements and quality improvements for EPPlusSoftware/EPPlus, focusing on data connectivity, formula reliability, and developer experience. Key outcomes include external data connections, query tables, and pivot table support (8.3.0); robustness improvements to AverageIf/SumIf with tests; XLOOKUP not-found handling improvements; Excel formula calculation fixes for calculated columns and general error handling; and the 8.3.1 release with bug fixes, performance and stability improvements, plus API documentation enhancements.
October 2025
2 Commits • 1 Features
Oct 1, 2025October 2025 highlights: Stabilized pivot table field management and upgraded EPPlus to 8.2.1 across all build configurations. Implemented tests validating pivot calculations and refresh behavior, and updated documentation to reflect changes. These changes improve reliability of pivot operations, streamline maintenance, and enable access to the library's latest features and fixes.
2 Commits • 1 Features
Oct 1, 2025October 2025 highlights: Stabilized pivot table field management and upgraded EPPlus to 8.2.1 across all build configurations. Implemented tests validating pivot calculations and refresh behavior, and updated documentation to reflect changes. These changes improve reliability of pivot operations, streamline maintenance, and enable access to the library's latest features and fixes.
October 2025
September 2025
8 Commits • 3 Features
Sep 1, 2025September 2025 EPPlus monthly highlights: delivered targeted fixes and platform-enabling features across the codebase to improve reliability, cross-platform configuration, data analysis capabilities, and loading performance. The work emphasized correctness of formulas, modernization of configuration management, enhanced pivot-table handling, expanded LAMBDA support, and asynchronous loading with cancellation support, driving measurable business value and improved developer efficiency.
September 2025
8 Commits • 3 Features
Sep 1, 2025September 2025 EPPlus monthly highlights: delivered targeted fixes and platform-enabling features across the codebase to improve reliability, cross-platform configuration, data analysis capabilities, and loading performance. The work emphasized correctness of formulas, modernization of configuration management, enhanced pivot-table handling, expanded LAMBDA support, and asynchronous loading with cancellation support, driving measurable business value and improved developer efficiency.
August 2025
7 Commits • 2 Features
Aug 1, 2025August 2025 monthly summary for EPPlus (EPPlusSoftware/EPPlus): Delivered stability fixes and feature enhancements across pivot data, charts, styling, and HTML export. Strengthened test coverage and release readiness, improving reliability for business users relying on pivot tables, advanced charting, and export workflows. Highlighted cross-cutting improvements in data validation, header/footer parsing, and range operations, with a clear path to future performance and scalability gains.
7 Commits • 2 Features
Aug 1, 2025August 2025 monthly summary for EPPlus (EPPlusSoftware/EPPlus): Delivered stability fixes and feature enhancements across pivot data, charts, styling, and HTML export. Strengthened test coverage and release readiness, improving reliability for business users relying on pivot tables, advanced charting, and export workflows. Highlighted cross-cutting improvements in data validation, header/footer parsing, and range operations, with a clear path to future performance and scalability gains.
August 2025
July 2025
2 Commits
Jul 1, 2025July 2025: Delivered targeted improvements and release readiness for EPPlus. The primary focus was upgrading the EPPlus library to version 8.0.7, addressing key formula calculation issues, function errors, and data type returns, plus enhancements to icon sets and dynamic array handling. Release notes were prepared and version bumps applied across build configurations. Included a documentation-only correction to fix issues description (VBA modules and AOT support) to ensure accuracy. These efforts improve Excel processing reliability, developer experience, and overall maintainability.
July 2025
2 Commits
Jul 1, 2025July 2025: Delivered targeted improvements and release readiness for EPPlus. The primary focus was upgrading the EPPlus library to version 8.0.7, addressing key formula calculation issues, function errors, and data type returns, plus enhancements to icon sets and dynamic array handling. Release notes were prepared and version bumps applied across build configurations. Included a documentation-only correction to fix issues description (VBA modules and AOT support) to ensure accuracy. These efforts improve Excel processing reliability, developer experience, and overall maintainability.
June 2025
8 Commits
Jun 1, 2025June 2025 performance summary for EPPlus. Focused on reliability and correctness improvements across core areas, culminating in the 8.0.6 maintenance release. Key work targeted signing, data model accuracy, Unicode handling, and PivotTable behavior to reduce customer-facing issues and improve overall stability for critical spreadsheets. Impact highlights: - Fewer signing errors and correct DigestInfo/AlgorithmIdentifier length handling for VBA project signing utility. - Robust range calculations in RangeHashset with tests for issue #2017. - Correct Unicode interpretation in string functions LEFT/RIGHT under Unicode mode, plus related error handling refactors. - Refined PivotTable filter insertion and disposal logic, with tests for issue #877 and improved disposal behavior in SaveAndCleanup. - Consolidated improvements in the EPPlus 8.0.6 release, including bug fixes across formulas, pivots, and Unicode handling, plus version/history updates. Technologies/skills demonstrated: - C# and .NET development - Unit testing and test-driven development - Refactoring and improved error handling - Release engineering and documentation updates
8 Commits
Jun 1, 2025June 2025 performance summary for EPPlus. Focused on reliability and correctness improvements across core areas, culminating in the 8.0.6 maintenance release. Key work targeted signing, data model accuracy, Unicode handling, and PivotTable behavior to reduce customer-facing issues and improve overall stability for critical spreadsheets. Impact highlights: - Fewer signing errors and correct DigestInfo/AlgorithmIdentifier length handling for VBA project signing utility. - Robust range calculations in RangeHashset with tests for issue #2017. - Correct Unicode interpretation in string functions LEFT/RIGHT under Unicode mode, plus related error handling refactors. - Refined PivotTable filter insertion and disposal logic, with tests for issue #877 and improved disposal behavior in SaveAndCleanup. - Consolidated improvements in the EPPlus 8.0.6 release, including bug fixes across formulas, pivots, and Unicode handling, plus version/history updates. Technologies/skills demonstrated: - C# and .NET development - Unit testing and test-driven development - Refactoring and improved error handling - Release engineering and documentation updates
June 2025
May 2025
10 Commits • 3 Features
May 1, 2025May 2025 monthly summary for EPPlus: Focused on reliability, accuracy, and release readiness. Deliverables include Excel Formula Engine Enhancements and Image Handling Improvements, plus Maintenance/Release Management for EPPlus 8.x. Fixed critical issues in Pivot Table caching and License Key Validation. Business impact: tighter formula correctness, accurate image rendering across formats, reduced workbook corruption risk, and smoother release processes.
May 2025
10 Commits • 3 Features
May 1, 2025May 2025 monthly summary for EPPlus: Focused on reliability, accuracy, and release readiness. Deliverables include Excel Formula Engine Enhancements and Image Handling Improvements, plus Maintenance/Release Management for EPPlus 8.x. Fixed critical issues in Pivot Table caching and License Key Validation. Business impact: tighter formula correctness, accurate image rendering across formats, reduced workbook corruption risk, and smoother release processes.
April 2025
8 Commits • 1 Features
Apr 1, 2025April 2025 monthly summary for EPPlus repository (EPPlusSoftware/EPPlus). This period focused on stabilizing core formula functionality, expanding dynamic array capabilities, and delivering release-ready bug fixes across versions 8.0.2 and 8.0.3. The work emphasized test coverage, reliability of Excel-like calculations, and improved maintainability through targeted refactors and documentation hygiene, translating into meaningful business value by reducing calculation risk and accelerating release cycles.
8 Commits • 1 Features
Apr 1, 2025April 2025 monthly summary for EPPlus repository (EPPlusSoftware/EPPlus). This period focused on stabilizing core formula functionality, expanding dynamic array capabilities, and delivering release-ready bug fixes across versions 8.0.2 and 8.0.3. The work emphasized test coverage, reliability of Excel-like calculations, and improved maintainability through targeted refactors and documentation hygiene, translating into meaningful business value by reducing calculation risk and accelerating release cycles.
April 2025
March 2025
15 Commits • 1 Features
Mar 1, 2025March 2025: Delivered EPPlus 8.x core engine stabilization and documentation readiness. Consolidated core engine fixes across EPPlus 8.x, including pivot cache handling, TimeSpan culture conversions, Range.Copy behavior for hidden rows, and formula parser robustness, complemented by improvements to OLE object handling, drawing/comment positioning, and expanded test coverage. Achieved release-readiness for EPPlus 8.x with licensing alignment and release notes, including 8.0.0-rc and 8.0.1 final, plus updated API manifests and docs.
March 2025
15 Commits • 1 Features
Mar 1, 2025March 2025: Delivered EPPlus 8.x core engine stabilization and documentation readiness. Consolidated core engine fixes across EPPlus 8.x, including pivot cache handling, TimeSpan culture conversions, Range.Copy behavior for hidden rows, and formula parser robustness, complemented by improvements to OLE object handling, drawing/comment positioning, and expanded test coverage. Achieved release-readiness for EPPlus 8.x with licensing alignment and release notes, including 8.0.0-rc and 8.0.1 final, plus updated API manifests and docs.
February 2025
24 Commits • 8 Features
Feb 1, 2025February 2025 – EPPlus (EPPlusSoftware/EPPlus) delivered a strong mix of platform upgrades, feature work, and stability improvements across the codebase. Key business value includes enabling .NET 9 readiness, refreshing dependencies, expanding data governance with Sensitivity Labels, and enhancing documentation and tests. The team focused on aligning with customers’ modernization timelines while improving reliability and maintainability.
24 Commits • 8 Features
Feb 1, 2025February 2025 – EPPlus (EPPlusSoftware/EPPlus) delivered a strong mix of platform upgrades, feature work, and stability improvements across the codebase. Key business value includes enabling .NET 9 readiness, refreshing dependencies, expanding data governance with Sensitivity Labels, and enhancing documentation and tests. The team focused on aligning with customers’ modernization timelines while improving reliability and maintainability.
February 2025
January 2025
8 Commits • 2 Features
Jan 1, 2025January 2025 — EPPlus project: Delivered pivotal enhancements to Pivot Table caching and source handling, improved CountIf stability, and upgraded platform dependencies to EPPlus 7.5.3 with .NET 9. These changes improve pivot reliability and performance, reduce maintenance burden, and position the library to leverage latest platform features. Tech stack and practices demonstrated: C#, .NET 9, code refactoring, null-safety, type-code-based comparisons, and dependency upgrades.
January 2025
8 Commits • 2 Features
Jan 1, 2025January 2025 — EPPlus project: Delivered pivotal enhancements to Pivot Table caching and source handling, improved CountIf stability, and upgraded platform dependencies to EPPlus 7.5.3 with .NET 9. These changes improve pivot reliability and performance, reduce maintenance burden, and position the library to leverage latest platform features. Tech stack and practices demonstrated: C#, .NET 9, code refactoring, null-safety, type-code-based comparisons, and dependency upgrades.
December 2024
20 Commits • 4 Features
Dec 1, 2024December 2024: Deliveries focused on reliability, performance, and feature parity for EPPlus. Key features delivered include dynamic filter correctness with Autofit performance improvements, and in-cell checkboxes with styling support. Pivot table handling was enhanced with a new cache-based comparison approach and robust item refresh logic. XML reading improvements ensured correct association of shared strings, numeric values, and styles, with tests added for decimal styling. Release/version updates were applied for EPPlus 7.5.2 and 8.0.0-beta across build configurations. These changes, alongside targeted test stability and code-quality refinements, reduced flaky behavior and improved overall data accuracy and performance.
20 Commits • 4 Features
Dec 1, 2024December 2024: Deliveries focused on reliability, performance, and feature parity for EPPlus. Key features delivered include dynamic filter correctness with Autofit performance improvements, and in-cell checkboxes with styling support. Pivot table handling was enhanced with a new cache-based comparison approach and robust item refresh logic. XML reading improvements ensured correct association of shared strings, numeric values, and styles, with tests added for decimal styling. Release/version updates were applied for EPPlus 7.5.2 and 8.0.0-beta across build configurations. These changes, alongside targeted test stability and code-quality refinements, reduced flaky behavior and improved overall data accuracy and performance.
December 2024
November 2024
17 Commits • 3 Features
Nov 1, 2024November 2024 monthly summary for EPPlusSoftware/EPPlus. This period delivered substantial feature improvements, major bug fixes, and enhanced release automation, driving reliability, maintainability, and faster time-to-market for users and teams. Key accomplishments include chart and styling enhancements with test coverage, pivot table and formula correctness fixes, and release/infrastructure improvements that streamlined CI and version propagation.
November 2024
17 Commits • 3 Features
Nov 1, 2024November 2024 monthly summary for EPPlusSoftware/EPPlus. This period delivered substantial feature improvements, major bug fixes, and enhanced release automation, driving reliability, maintainability, and faster time-to-market for users and teams. Key accomplishments include chart and styling enhancements with test coverage, pivot table and formula correctness fixes, and release/infrastructure improvements that streamlined CI and version propagation.
Activity
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Quality Metrics
Correctness89.6%
Maintainability85.4%
Architecture83.6%
Performance81.0%
AI Usage20.8%
Skills & Technologies
Programming Languages
C#MarkdownPowerShellXMLYAMLcscsprojmdyml
Technical Skills
.NET Build .NET Development Build Configuration C# NuGet Package Management.NET.NET Core.NET Development.NET developmentAPI DesignAPI DevelopmentAPI DocumentationAPI IntegrationAsync ProgrammingAsynchronous Programming
Repositories Contributed To
Overview of all repositories you've contributed to across your timeline