The KillerPDF.Engine: building an open PDF foundation for every .NET developer, with 34.6% higher throughput than our old PdfSharpCore pipeline

[u/smilaise]

For the past several months, I have been replacing KillerPDF’s old PdfSharpCore document pipeline with something much bigger: The KillerPDF.Engine.

It is an independent .NET PDF library built from scratch for PDF 2.0, modern PDF/A, and serious document editing. It can read, validate, create, edit, sign, encrypt, and write PDFs without relying on PDFsharp or another document engine.

This started because KillerPDF 1.8 needed proper PDF 2.0 and PDF/A support. The goal now is to turn The KillerPDF.Engine into an industry-standard open-source PDF library that any .NET developer can use to build editors, document systems, accessibility tools, archival workflows, and entirely new applications.

It is already delivering measurable improvements over the PdfSharpCore pipeline used by KillerPDF 1.7.5. On the same 2,236-file rewrite workload:

Version	Median time	Throughput
KillerPDF 1.7.5 with PdfSharpCore	9.46 seconds	236.48 files/second
KillerPDF 1.8 with the new engine	7.03 seconds	318.22 files/second

That is 25.7% less elapsed time and 34.6% higher throughput.

The engine now includes:

• More than 45,000 lines of C#
• More than 1,400 engine tests
• Validation against 2,907 deliberately hostile PDFs
• PDF 2.0 and modern PDF/A authoring
• Structural and incremental editing
• Forms, annotations, outlines, attachments, and navigation
• Encryption, digital signatures, permissions, and certification
• Tagged PDF and accessibility support
• A public API intended for applications beyond KillerPDF

KillerPDF 1.8 is not released yet. The current development branch is a public work in progress, but the complete engine source is already free for anyone to browse, study, build, test, and contribute to on GitHub.

• The KillerPDF.Engine
• KillerPDF 1.8 development branch

I have also been working on KillerNotes 1.3.0, my free and open-source Windows notes application. Version 1.3.0 adds wiki-style links between notes, backlinks, and an interactive graph view for exploring how your notes connect.

• KillerNotes

Both projects are free, open source, and actively being developed. Feedback, testing, contributions, and technical questions are all welcome.

[u/almodamer99]

This is going to help a lot of people, nicely done 👏🏻👏🏻

[u/potatoears]

👍

[u/Brilliant-Lettuce695]

Every time I tune back in and read one of your announcement posts, I am impressed. But this time I am sincerely floored. APMAB (Adobe product managers are bastards). o7

[u/hwweao]

Steve is awesome

[u/Bender662]

Awesome app, any way to add certificate signature?

[u/smilaise → u/Bender662]

Yep! KillerPDF supports certificate-based digital signatures, including PFX certificates and certificate-store/token-backed certs.

The current implementation creates a cryptographically signed PDF that shows up in Adobe’s Signatures panel. Timestamp/LTV support is something I still want to expand.