Hisui PDF

A cross-platform desktop PDF editor built on a fully free/MIT-licensed stack.

Hisui PDF lets you reorganise, annotate, redact and protect PDF documents from a single Avalonia desktop app that runs on Windows, Linux and macOS.

Download

winget (Windows)

winget install Fileman.HisuiPDF

Upgrade later with winget upgrade Fileman.HisuiPDF.

Release assets

Grab a ready-to-run build from the Releases page — the binaries are self-contained, so no .NET install is required.

Platform	Asset
Windows x64 (installer)	HisuiPDF-Setup-X.Y.N-win-x64.exe (asks for UAC up front; works where AppLocker blocks unsigned MSIs) or HisuiPDF-X.Y.N-win-x64.msi
Windows x64 (portable)	Hisui.Pdf-vX.Y.N-win-x64.zip
Linux x64	Hisui.Pdf-vX.Y.N-linux-x64.tar.gz
macOS (Intel)	Hisui.Pdf-vX.Y.N-osx-x64.tar.gz
macOS (Apple Silicon)	Hisui.Pdf-vX.Y.N-osx-arm64.tar.gz

The release tag is vX.Y.N: X.Y is chosen when releasing, N is the commit count of the released build.

On Windows run the MSI (it is unsigned, so SmartScreen/UAC will warn), or unpack the zip. On Linux/macOS unpack the archive and run Hisui.Pdf.App. On macOS the binary is unsigned, so on first launch right-click → Open (or run xattr -dr com.apple.quarantine Hisui.Pdf.App).

Releases started with the prerelease option are published as pre-releases.

Updates

Hisui PDF checks GitHub for a newer stable release at startup (disable with "CheckForUpdates": false in %APPDATA%\Hisui.PDF\settings.json) and from ? Help → Check for updates…. On Windows, accepting downloads the MSI and runs it as an in-place upgrade; on other platforms it opens the release page. Pre-releases are never offered.

Features

• Pages — merge, split, extract, reorder, rotate and delete pages, with non-destructive editing and full undo/redo. Multiple documents in tabs, with an unsaved-changes prompt on close.
• Annotations — highlight, rectangle, free text, sticky notes, image overlays, editable watermarks and header/footer with page, date and Bates tokens (all undoable).
• Comments, bookmarks & links — real PDF comments with replies and a comments panel; bookmarks panel (add, nest, rename, reorder); link tool with clickable links. Saving keeps outline, links, tags and metadata.
• Reusable signatures — build a library of signatures (draw freehand, import a PNG, or type cursive text) and reuse them across documents.
• Digital signatures (experimental) — PAdES signing with a PFX certificate, appended as an incremental update so existing signatures stay valid; sign into empty signature fields or invisibly; verify signatures.
• Forms — fill AcroForm fields in place (formats, required/invalid highlight); automatic field detection; layout mode with multi-select, align, resize, tab order and field properties; import/export data (XFDF, FDF, CSV), reset and flatten.
• Text editing — replace a word in place (redact-and-retype).
• Redaction — secure redaction that rasterises the page and removes the underlying text/vector content; find-and-redact by pattern (tax code, IBAN, VAT, e-mail, phone, date, custom regex).
• Compare — text comparison with another PDF, with marks and a report.
• Standards — preflight and conversion to PDF 1.4–2.0, PDF/A-1b/2b/2u/3b/3u, PDF/UA-1, PDF/X-4, plus an accessibility check.
• Security & metadata — AES-256 encryption, password removal, document properties.
• Print & compress — print with preview and options (printer, copies, duplex, page range); reduce file size by recompressing images.
• Export & extraction — convert to Word (.docx), Excel (.xlsx) and PowerPoint (.pptx); pull out text (with coordinates) and embedded images.
• OCR — turn scanned (image-only) PDFs into searchable PDFs by adding an invisible, selectable text layer (Tesseract, parallel across pages). Scanned pages are detected automatically; extra languages can be downloaded on demand.
• Batch processing — apply one operation (OCR, compression, PDF/A, Word, Excel, PowerPoint, text) to many PDFs; originals are never changed.
• Recent files — start page with a table of recent documents (thumbnail, folder, last opened, size) and pinning.
• Localization — English and Italian UI, switchable at runtime; light, dark or system theme (light theme meets WCAG AA contrast).
• Help & diagnostics — the ? Help button reports a problem or requests a feature on GitHub, checks for updates and opens View log… (warnings, errors and stack traces from %APPDATA%\Hisui.PDF\hisui.log).

Tech stack

• .NET 10 / C#
• Avalonia 12 — cross-platform UI
• PDFsharp — structural & write operations
• PdfPig — text/image extraction
• Open XML SDK — Word (.docx) export
• PDFtoImage (PDFium) — page rendering
• Tesseract — OCR for scanned PDFs
• SkiaSharp — raster compositing
• CommunityToolkit.Mvvm + Microsoft.Extensions.Hosting — MVVM & DI

Project structure

Project	Target	Role
src/Hisui.Pdf.Core	net10.0	PDF engine, no UI dependencies
src/Hisui.Pdf.App	net10.0	Avalonia desktop app (MVVM)
src/Hisui.Pdf.Installer.Win	WiX 4	Windows MSI installer
tests/Hisui.Pdf.Core.Tests	net10.0	xUnit v3 tests

Build & run

# Build
dotnet build Hisui.Pdf.slnx

# Run the app
dotnet run --project src/Hisui.Pdf.App

# Run the tests (xUnit v3 on Microsoft Testing Platform — run the test exe)
dotnet test Hisui.Pdf.slnx

Packaging

Installer/package scripts live in build/: package-msi.ps1 (signed MSI via WiX), package-win.ps1, package-linux.sh, package-osx.sh. Releases are built by the GitHub Actions Release workflow, started manually from the Actions tab (or gh workflow run release.yml -f version=0.1). It creates the vX.Y.N tag itself.

OCR setup

OCR works out of the box. The English and Italian language data (eng/ita, the tessdata_fast models) ships in a tessdata folder next to the executable, and the native engine binaries are bundled on Windows via the Tesseract package.

• More languages — main menu → Preferences → OCR languages… downloads other languages on demand from tessdata_fast or imports a .traineddata file offline. You can also drop *.traineddata files into the tessdata folder next to the app (or point TESSDATA_PREFIX at them).
• Native libraries on Linux/macOS — install the system Tesseract/Leptonica: on Linux libtesseract/libleptonica, on macOS brew install tesseract leptonica.

If a language or native library is missing the app reports a clear message instead of failing — the rest of the editor keeps working.

License

Hisui PDF is released under the MIT License.

It bundles third-party components under permissive licenses (MIT, Apache-2.0, BSD-3-Clause) and the Inter font (SIL OFL 1.1). See THIRD-PARTY-NOTICES.txt for the full attributions.