head to head · open source
KillerPDF vs ZenConverter
KillerPDF has 4,289 GitHub stars, 342 forks, 38 open issues and last shipped yesterday. ZenConverter has 1,842 stars, 64 forks, 3 open issues and last shipped 3 days ago. KillerPDF leads on adoption by 133% (4,289 vs 1,842 stars). KillerPDF is written in C# under GPL-3.0; ZenConverter is written in Kotlin under AGPL-3.0. KillerPDF has attracted 8% as many forks as stars, ZenConverter 3%. KillerPDF was the more recently maintained of the two, and both are self-hostable with no licence fee.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
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Side by side
| KillerPDF | ZenConverter | |
|---|---|---|
| GitHub stars | ★ 4.3K | ★ 1.8K |
| License | GPL-3.0 | AGPL-3.0 |
| Written in | C# | Kotlin |
| Last push | 2026-11-02 | 2026-10-31 |
| Forks | ⑂ 342 | ⑂ 64 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick KillerPDF if
- You weight community size — 4.3K stars and counting
- You want the GPL-3.0 license terms
- Your stack matches C#
- You value the larger contributor base for long-term maintenance
pick ZenConverter if
- You want the ZenConverter feature set and don't need the biggest community
- You prefer the AGPL-3.0 license terms
- Your stack matches Kotlin
- You evaluated both and ZenConverter fits your workflow better
About KillerPDF
KillerPDF is a free, open source PDF editor for Windows. View, annotate, OCR, merge, split, edit text, draw, sign, fill forms, print, flatten, and open password protected PDFs without an Adobe subscription. Choose the compact Windows installer or the self contained portable edition. Document processing stays on your computer, with no telemetry. Full how tos live on the help page; internals, formats, and limits on the technical page. The KillerPDF.Engine KillerPDF 1.8 introduces The KillerPDF.Engine, an independent and reusable .NET library for PDF 2.0, PDF/A, and PDF/UA document processing. It is a first class…
read the full KillerPDF overview →
About ZenConverter
ZenConverter Private, local first file conversion for Android. English 中文 ZenConverter is a local file converter for Android. Pick a file on your phone, convert it on your phone, and keep it off someone else's server. The app is built with native Kotlin and Jetpack Compose. File access goes through Android's Storage Access Framework, and longer jobs run in a foreground service. The app deliberately stays narrow: supported routes are verified on a physical Android device, and their known limits are written down instead of hidden. Note: very large media files still need adequate free storage, memory, and power…
read the full ZenConverter overview →
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Frequently asked questions
Is KillerPDF or ZenConverter more popular?
KillerPDF has 4,289 GitHub stars and ZenConverter has 1,842. KillerPDF has the larger community by that measure.
Are KillerPDF and ZenConverter free?
Both are open source. KillerPDF is licensed under GPL-3.0 and ZenConverter under AGPL-3.0. Neither carries a licence fee.
What is the difference between KillerPDF and ZenConverter?
KillerPDF is written in C# and ZenConverter in Kotlin. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, KillerPDF or ZenConverter?
Choose KillerPDF if you want the larger community (4,289 stars) or its GPL-3.0 licence terms. Choose ZenConverter if its feature set, stack or AGPL-3.0 licence fits better. Both are self-hostable.