head to head · open source
KillerPDF vs IronCalc
KillerPDF has 4,289 GitHub stars, 342 forks, 38 open issues and last shipped yesterday. IronCalc has 4,246 stars, 217 forks, 256 open issues and last shipped yesterday. KillerPDF leads on adoption by 1% (4,289 vs 4,246 stars). KillerPDF is written in C# under GPL-3.0; IronCalc is written in Rust under Apache-2.0. KillerPDF has attracted 8% as many forks as stars, IronCalc 5%. 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 | IronCalc | |
|---|---|---|
| GitHub stars | ★ 4.3K | ★ 4.2K |
| License | GPL-3.0 | Apache-2.0 |
| Written in | C# | Rust |
| Last push | 2026-11-02 | 2026-11-02 |
| Forks | ⑂ 342 | ⑂ 217 |
| 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 IronCalc if
- You want the IronCalc feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches Rust
- You evaluated both and IronCalc 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 IronCalc
IronCalc [![MIT licensed][mit badge]][mit url] [![Apache 2.0 licensed][apache badge]][apache url] [![Build Status][actions badge]][actions url] [![Code coverage][codecov badge]][codecov url] [![docs badge]][docs url] [![Discord chat][discord badge]][discord url] [mit badge]: [mit url]: [apache badge]: [apache url]: [codecov badge]: [codecov url]: [actions badge]: [actions url]: [docs url]: [docs badge]: [discord badge]: [discord url]: IronCalc is a new, modern, work in progress spreadsheet engine and set of tools to work with spreadsheets in diverse settings. This repository contains the main engine and the xlsx…
read the full IronCalc overview →
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Frequently asked questions
Is KillerPDF or IronCalc more popular?
KillerPDF has 4,289 GitHub stars and IronCalc has 4,246. KillerPDF has the larger community by that measure.
Are KillerPDF and IronCalc free?
Both are open source. KillerPDF is licensed under GPL-3.0 and IronCalc under Apache-2.0. Neither carries a licence fee.
What is the difference between KillerPDF and IronCalc ?
KillerPDF is written in C# and IronCalc in Rust. 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 IronCalc ?
Choose KillerPDF if you want the larger community (4,289 stars) or its GPL-3.0 licence terms. Choose IronCalc if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.