KillerPDF: a GPLv3 Windows PDF editor running on its own PDF engine
Free and open-source PDF editor for Windows with a built-in PDF 2.0 engine. View, annotate, OCR, merge, split, crop, rotate, compare, edit text, draw, sign, fill forms, print, flatten, and open password-protected PDFs without a subscription.
At a glance
- What is it?
- A GPLv3 Windows PDF editor that runs on its own PDF engine for rendering, text extraction, editing and document processing, with OCR, redaction, signing, form tools and a command line.
- Who is it for?
- KillerPDF suits a Windows user who wants a local PDF editor with OCR, page manipulation, redaction, signing and form tools, without an account. Check a few things first.
- Can I use it commercially?
- Yes, with conditions. GPL-3.0 is a copyleft licence: if you distribute software that includes it, you must release that software's source code under the same licence. Running it internally without distributing it does not trigger that obligation.
- Is it still maintained?
- Yes. The repository last received commits 4 days ago.
- What is it written in?
- Mainly C#, according to GitHub's language statistics.
Answers come from the project's GitHub data, last synced on November 14, 2026, and from our analysis. They are not legal advice.
Star history
- SteveTheKiller/KillerPDF4,374 ★ · +388
| Repository | 2026-09-24 | 2026-11-14 |
|---|---|---|
| SteveTheKiller/KillerPDF | 4k | 4.4k |
388 Stars in the last 51 days, measured from the daily GitHub snapshot. Compare with other projects
Editorial analysis
The source link is pinned and the two binary links are not
The README's licence section links a corresponding-source archive for the GPLv3 licence, and the two parts of that link do not agree: the link text names the 1.9.0 corresponding-source archive, while the URL points to KillerPDF-1.9.2-src.zip under the v1.9.2 release. The README does not link installers directly. It sends readers to killerpdf.net for downloads, says KillerPDF can be installed, run as a portable package, or obtained from the Microsoft Store, Chocolatey or WinGet, and says the GitHub release assets include every package and the source archives. Releases move quickly: v1.9.0 on 2026-10-29, v1.9.1 on 2026-10-31 and v1.9.2 on 2026-11-02.
The command line strips PDF protection and can take the password as an argument
The README lists the command line among the ways to repeat work, alongside guided tasks, macros, watched folders and data merge, but it does not list individual commands or flags. On protected files, the repository description says KillerPDF can open password-protected PDFs, and the feature list says it can protect copies with passwords or certificate recipients.
No telemetry is a claim about telemetry, and there are three outbound paths
The README says KillerPDF works locally and without an account. It does not make a telemetry statement or describe an update check. The one network activity it names is that OCR language models download separately from inside the app.
A conformance corpus is a gate, and it names one validator
The repository has a top-level validation/ directory, but the README does not describe a conformance corpus or a release gate. The documented tests are the engine test project and the application test project, run with dotnet test, and a few app tests open WPF windows and need an unlocked desktop.
The built-in engine is a document model sitting on two other PDF libraries
The README says version 1.9 runs on KillerPDF's own PDF engine for rendering, text extraction, editing and document processing, and the repository description calls it a built-in PDF 2.0 engine. The engine lives in the engine/ directory, with its own documentation (engine/README.md), its own changelog (engine/CHANGELOG.md) and its own test project (engine/KillerPdf.Engine.Tests).
Two changelogs and one tag namespace named for the application
The README links an application changelog (CHANGELOG.md) and a separate engine changelog (engine/CHANGELOG.md), alongside the engine documentation. Releases are tagged v1.9.0, v1.9.1 and v1.9.2 and named for the application (for example KillerPDF v1.9.2), so the tag list does not name an engine version; the engine changelog is the place to look for engine changes.
The documented source build produces neither shipping artefact
The README's build and test steps use Windows and the .NET SDK selected by global.json:
git clone https://github.com/SteveTheKiller/KillerPDF.git
cd KillerPDF
dotnet restore KillerPDF.csproj
dotnet build KillerPDF.csproj -c Release
dotnet test engine/KillerPdf.Engine.Tests/KillerPdf.Engine.Tests.csproj
dotnet test KillerPDF.Tests/KillerPDF.Tests.csprojA few app tests open WPF windows, so the README says to run them on an unlocked desktop, follow the prerequisites in the UI smoke guide, and build and test one checkout at a time. The README does not say how the installer and portable packages are built; the repository root has a release.ps1 script.
Thirteen themes make thirty-three looks, and a partial translation is accepted on purpose
The README says you can choose from 13 themes and 20 interface languages, customize shortcuts, and scale the whole interface. The sidebar docks on any side of the window, and tabs can sit at the top or the bottom. Documents can be read in tabs or split panes. For translators, the repository has a Strings/ directory and a TRANSLATING.md guide linked from the README.
Editorial conclusion
KillerPDF suits a Windows user who wants a local PDF editor with OCR, page manipulation, redaction, signing and form tools, without an account. Check a few things first. It is a Windows application, and building it needs Windows and the .NET SDK selected by global.json. Version 1.9 runs on KillerPDF's own PDF engine for rendering, text extraction, editing and document processing. OCR language models download separately from inside the app. And the README's corresponding-source link is labelled 1.9.0 while pointing to the 1.9.2 archive, so check that the source archive you download matches the build you install.
Frequently asked questions
What is KillerPDF?
A free, open-source PDF editor for Windows, released under GPLv3. It reads, annotates, edits, organizes, signs, redacts and converts documents, runs OCR, fills forms and opens password-protected PDFs. The README says it works locally and without an account.
Does KillerPDF send telemetry?
The README makes no telemetry statement. It says KillerPDF works locally and without an account, and that OCR language models download separately from inside the app.
How do I install KillerPDF?
Downloads are at killerpdf.net. You can install it, run the portable package, or get it from the Microsoft Store, Chocolatey or WinGet, and the GitHub release assets include every package and the source archives.
What is The KillerPDF.Engine?
KillerPDF's own PDF engine, which the README says version 1.9 uses for rendering, text extraction, editing and document processing. It lives in the engine/ directory with its own documentation, changelog and test project.
How is KillerPDF tested?
The README's build section runs dotnet test on the engine test project and the application test project. A few app tests open WPF windows, so they should run on an unlocked desktop following the UI smoke guide's prerequisites, one checkout at a time.
Official sources
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