Guust Ysebie
Software Engineer at Apryse
Ghent Metropolitan Area Belgium
Summary
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RockstarGuust Ysebie is a software engineer based in the Ghent metropolitan area with eight years of experience specializing in backend development and PDF processing. At Apryse he works on robust document tooling, drawing on deep practical knowledge of PDF internals gained from contributions to the widely used iText projects for both Java and .NET. His open-source fixes focus on stability and correctness—rebuilding cross-reference tables, handling PdfPagesTree edge cases, and resolving subtle encoding and datetime issues—demonstrating attention to low-level details that often break in production. Guust blends pragmatic bug-fixing with API improvements like text-to-glyph space utilities, showing an inclination to make libraries both more reliable and easier to use. Colleagues rely on him for tackling thorny, platform-specific bugs and improving long-lived developer tooling rather than flashy greenfield features.
7 years of coding experience
Stackoverflow
13reputation
187reached
0answers
3questions
Github Skills (17)
debugging10
debug10
java10
javas10
pdf-processing10
dotnet-core10
pdf-generation10
pdf-manipulation10
csharp10
unit-testing9
pdf9
base64-encoding8
gzip7
netbeans6
scenebuilder6
Programming languages (8)
Github contributions (5)
itext/itext-dotnet
Nov 2022 - Jan 2023
iText for .NET is the .NET version of the iText library, formerly known as iTextSharp, which it replaces. iText represents the next level of SDKs for developers that want to take advantage of the benefits PDF can bring. Equipped with a better document engine, high and low-level programming capabilities and the ability to create, edit and enha
Role in this project:
Back-end Developer
Back-end DeveloperContributions:1 release, 8 commits in 1 month
Contributions summary:Guust primarily contributed to the iText .NET library by addressing several issues related to PDF processing and manipulation. Their work involved fixing bugs in the `PdfPagesTree` and `PdfReader` classes, ensuring correct cross-reference table rebuilding, and managing trailer dictionary modifications. The commits demonstrate a focus on improving the library's stability, correctness, and handling of PDF structure inconsistencies, particularly within the iText.Kernel project. Additional contributions include introduction of static methods for text glyph space conversions.
abilitypdf-generationaccessibilitypdfuacredit
itext/itext-java
Nov 2022 - Jan 2023
iText for Java represents the next level of SDKs for developers that want to take advantage of the benefits PDF can bring. Equipped with a better document engine, high and low-level programming capabilities and the ability to create, edit and enhance PDF documents, iText can be a boon to nearly every workflow.
Role in this project:Backend Developer
Backend DeveloperContributions:1 release, 10 commits, 2 PRs in 2 months
Contributions summary:Guust primarily focused on improving the iText-java library by addressing bugs and enhancing its functionality. They fixed issues related to OS-specific flags in the Base64 encoding, potential timing failures in the DateTimeUtil methods, and invalid PdfPagesTree handling. They also worked on rebuilding cross-reference tables and introduced static methods for text-to-glyph space conversions. These changes suggest a focus on improving the PDF generation and manipulation capabilities of the library.
signature-padpdf-documentssignatureabilitypdf-generation
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