Jan Källman
CEO And Founder at EPPlus Software
Stockholm County, Sweden
Summary
🤩
RockstarJan Källman is a seasoned software leader and entrepreneur with 16 years of experience, currently CEO and co-founder of EPPlus Software in Stockholm, commercializing the world’s most popular open-source .NET library for Excel. He combines hands-on backend expertise—deeply familiar with worksheet, formula, pivot table and chart internals—with product and consulting leadership, having founded the company with a focus on both services and commercial offerings around EPPlus. His long-term contributions to the EPPlus codebase include fixing complex rendering, rich text and memory issues and improving core cell-store and drawing behavior, demonstrating an unusual blend of low-level debugging and architectural judgment. Prior to EPPlus Software he worked as a solutions architect, helping translate business requirements into robust .NET systems. He is pragmatic, detail-oriented, and especially skilled at stabilizing and scaling libraries that power enterprise spreadsheet automation.
16 years of coding experience
Stackoverflow
401reputation
1.5mreached
2answers
0questions
excel
top-5%
Github Skills (16)
data-structures10
debugging10
formula10
debug10
develop10
parsing10
csharp10
parse10
data-structure10
formulas10
dotnet-core10
netframework10
excel9
xml9
performance-optimization8
Programming languages (4)
Github contributions (5)
JanKallman/EPPlus
Nov 2009 - Mar 2020
Create advanced Excel spreadsheets using .NET
Role in this project:
Back-end Developer
Back-end DeveloperContributions:3 releases, 438 commits, 18 PRs in 10 years 5 months
Contributions summary:Jan contributed primarily to the EPPlus library's core functionality, particularly focusing on improvements to worksheet, formula, and data structure handling. Their work involved addressing specific bugs, refactoring code related to the cell store, and implementing new features related to pivot tables, table handling, and chart rendering. The user's contributions directly improved the library's stability and functionality, as evidenced by fixes to address parsing issues and improved performance within key aspects of EPPlus's core functionality.
dotnetooxmlopenxmlcsharpvba
EPPlusSoftware/EPPlus
Jan 2020 - Jan 2023
EPPlus-Excel spreadsheets for .NET
Role in this project:Back-end Developer
Back-end DeveloperContributions:80 releases, 58 reviews, 1363 commits in 3 years
Contributions summary:Jan contributed to fixing bugs related to the handling of drawing elements and improving the rendering process within the EPPlus Excel library. The user's commits focused on resolving issues concerning the display and handling of rich text, comments, and table styles in the generated Excel files. The contributions addressed the correct use of attributes when saving information, as well as handling of memory spikes, and involved changes to the ExcelWorksheet, ExcelRangeBase, ExcelDrawings, and ExcelRichText classes.
dotnetnetstandardnetframeworkooxmlopenxml
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