Lankir

A modern, high-performance PDF editor for Linux with advanced digital signature support

Features • Installation • Usage • CLI Reference • Building • Contributing • License

Overview

Lankir is a desktop PDF editor built specifically for Linux, combining the power of Go with a modern web-based UI through Wails. It provides comprehensive PDF viewing capabilities and enterprise-grade digital signature support, including hardware tokens (smart cards) and multiple certificate backends.

The same binary works as both a GUI application and a CLI tool, making it perfect for both interactive use and automated workflows.

Key Highlights

🖥️ Native Desktop App — Fast, responsive UI with GTK3 integration
🔐 Advanced Digital Signatures — Support for PKCS#11, PKCS#12, and NSS certificates
💻 Dual Mode Operation — GUI for interactive use, CLI for scripting and automation
📦 Portable Deployment — AppImage available for distribution-agnostic installation
⚡ High Performance — Go backend with MuPDF for fast PDF rendering

Features

PDF Viewing & Operations

Open and view PDF documents with smooth rendering
Page thumbnails and navigation
Zoom controls with customizable default levels
Extract PDF metadata (title, author, page count)
Render pages to PNG at custom DPI
Generate thumbnails for preview

Digital Signatures

Sign PDFs with X.509 certificates
Multiple certificate sources:
- PKCS#12 files (.p12, .pfx)
- PKCS#11 hardware tokens (smart cards, USB tokens, HSMs)
- NSS databases (Firefox/Thunderbird certificates)
Visible and invisible signatures with customizable appearance
Signature profiles for reusable signing configurations
Signature verification with full certificate chain validation
Position control for visible signatures (page, coordinates, size)
Custom signature appearance (signer name, timestamp, location, logo)

Certificate Management

List certificates from all configured sources
Filter by source, validity, or search term
View detailed certificate information
Validate certificate status and key usage
Auto-discovery of system certificate stores

Configuration

Persistent settings stored in ~/.config/lankir/
Theme selection (light/dark)
Customizable certificate store paths
Configurable PKCS#11 module libraries
Multiple signature profiles

Installation

Option 1: Package Manager (Recommended)

Add the Lankir repository to be able to install it and receive automatic updates:

Debian/Ubuntu:

# Add repository
curl -1sLf 'https://dl.cloudsmith.io/public/matbe34/lankir/setup.deb.sh' | sudo -E bash

# Install Lankir
sudo apt update
sudo apt install lankir

Fedora/RHEL/AlmaLinux:

# Add repository
curl -1sLf 'https://dl.cloudsmith.io/public/matbe34/lankir/setup.rpm.sh' | sudo -E bash

# Install Lankir
sudo dnf install lankir

Supported distributions:

Ubuntu: 24.04 (Noble), 22.04 (Jammy), 20.04 (Focal)
Debian: 12 (Bookworm), 11 (Bullseye)
Fedora: 40, 39
RHEL/AlmaLinux/Rocky: 9, 8

Option 2: Download Package (.deb / .rpm)

Download and install the package for your distribution from Releases:

Debian/Ubuntu (.deb):

# Download the .deb package
wget https://github.com/Matbe34/lankir/releases/download/v0.1.0/lankir_0.1.0_amd64.deb

# Install with dependencies
sudo apt install ./lankir_0.1.0_amd64.deb

Fedora/RHEL (.rpm):

# Download and install
wget https://github.com/Matbe34/lankir/releases/download/v0.1.0/lankir-0.1.0-1.x86_64.rpm
sudo dnf install ./lankir-0.1.0-1.x86_64.rpm

openSUSE (.rpm):

wget https://github.com/Matbe34/lankir/releases/download/v0.1.0/lankir-0.1.0-1.x86_64.rpm
sudo zypper install ./lankir-0.1.0-1.x86_64.rpm

Note: Manual package installation does not provide automatic updates. Use Option 1 for auto-updates.

Option 3: AppImage

The AppImage is fully self-contained and works on any modern Linux distribution:

# Download the AppImage
wget https://github.com/Matbe34/lankir/releases/download/v0.1.0/lankir-0.1.0-x86_64.AppImage

# Make it executable
chmod +x lankir-0.1.0-x86_64.AppImage

# Run it
./lankir-0.1.0-x86_64.AppImage

Option 4: Static Binary

For the portable binary, install the required runtime dependencies:

Ubuntu/Debian:

sudo apt install libgtk-3-0 libwebkit2gtk-4.0-37 libnss3

Fedora/RHEL:

sudo dnf install gtk3 webkit2gtk3 nss

Arch Linux:

sudo pacman -S gtk3 webkit2gtk nss

Then download and run the binary:

# Download
wget https://github.com/Matbe34/lankir/releases/download/v0.1.0/lankir_static

# Make executable and move to PATH
chmod +x lankir_static
sudo mv lankir_static /usr/local/bin/lankir

Usage

Launching the GUI

Simply run the application without arguments:

lankir

Or explicitly:

lankir gui

Using the CLI

Add any command to use CLI mode:

# Get help
lankir --help

# PDF operations
lankir pdf info document.pdf

# Certificate management
lankir cert list

# Sign a document
lankir sign pdf document.pdf signed.pdf --fingerprint <cert-fingerprint>

Keyboard Shortcuts

Shortcut	Action
`Ctrl+O`	Open PDF
`Alt+S`	Sign PDF
`Ctrl++`	Zoom in
`Ctrl+-`	Zoom out
`Ctrl+0`	Reset zoom

CLI Reference

Global Flags

lankir [command] [flags]

Flags:
  -v, --verbose   Enable verbose logging (debug level)
      --json      Output logs in JSON format (for scripting)
  -h, --help      Help for lankir

PDF Operations

# Display PDF metadata
lankir pdf info document.pdf
lankir pdf info document.pdf --json

# Show page dimensions
lankir pdf pages document.pdf

# Render a page to PNG
lankir pdf render document.pdf --page 1 --dpi 300 --output page1.png

# Generate thumbnail
lankir pdf thumbnail document.pdf --width 400 --output thumb.png

Certificate Management

# List all certificates
lankir cert list

# List only valid certificates that can sign
lankir cert list --valid-only

# Filter by source
lankir cert list --source pkcs11
lankir cert list --source pkcs12
lankir cert list --source nss

# Search certificates by name
lankir cert search "John Doe"

# Show detailed certificate info
lankir cert info <fingerprint>

# JSON output for scripting
lankir cert list --json

Digital Signatures

# Sign with invisible signature (default)
lankir sign pdf document.pdf signed.pdf --fingerprint <fingerprint>

# Sign with PIN (for hardware tokens)
lankir sign pdf document.pdf signed.pdf --fingerprint <fingerprint> --pin <pin>

# Sign with a specific profile
lankir sign pdf document.pdf signed.pdf --fingerprint <fingerprint> --profile default-visible

# Sign with custom visible signature position
lankir sign pdf document.pdf signed.pdf --fingerprint <fingerprint> \
  --page 1 --x 400 --y 50 --width 200 --height 80

# Verify signatures in a PDF
lankir sign verify document.pdf
lankir sign verify document.pdf --json

# List signature profiles
lankir sign profile-list

# Show profile details
lankir sign profile-info default-visible

Configuration

# View all configuration
lankir config get

# Get specific setting
lankir config get theme

# Set configuration value
lankir config set theme dark
lankir config set defaultZoom 150

# Reset to defaults
lankir config reset

Building

Prerequisites

Go 1.24 or higher
Wails CLI v2 (go install github.com/wailsapp/wails/v2/cmd/wails@latest)
Task runner (go install github.com/go-task/task/v3/cmd/task@latest)
Node.js (for frontend build)

System libraries:

# Ubuntu/Debian
sudo apt install build-essential libgtk-3-dev libwebkit2gtk-4.0-dev libnss3-dev

# Fedora
sudo dnf install gtk3-devel webkit2gtk3-devel nss-devel

# Arch
sudo pacman -S gtk3 webkit2gtk nss

Build Commands

# Clone the repository
git clone https://github.com/Matbe34/lankir.git
cd lankir

# Install Go dependencies
go mod download

# Development mode with hot reload
task dev

# Production build (requires GTK3 on target)
task build

# Portable static build
task build-static

# AppImage (fully portable)
task appimage

Available Tasks

Task	Description
`task dev`	Development mode with hot reload
`task build`	Production build
`task build-static`	Portable binary for distribution
`task appimage`	Self-contained AppImage
`task test`	Run all tests (Go + JavaScript)
`task test-backend`	Run Go tests only
`task test-frontend`	Run JavaScript tests only
`task test-coverage`	Generate coverage reports
`task lint`	Run linters
`task clean`	Remove build artifacts
`task clean-all`	Deep clean including caches

Architecture

lankir/
├── main.go                     # Entry point (GUI/CLI router)
├── app.go                      # Wails app wrapper
├── cmd/cli/                    # Cobra CLI commands
│   ├── root.go                 # Root command & logging setup
│   ├── pdf.go                  # PDF operations
│   ├── cert.go                 # Certificate management
│   ├── sign.go                 # Signing operations
│   └── config.go               # Configuration commands
├── internal/
│   ├── config/                 # Configuration service
│   ├── pdf/                    # PDF service (go-fitz/MuPDF)
│   │   ├── service.go          # PDF operations
│   │   └── recent.go           # Recent files tracking
│   └── signature/              # Signature subsystem
│       ├── service.go          # Main signature service
│       ├── profile.go          # Signature profiles
│       ├── signing.go          # PDF signing logic
│       ├── verification.go     # Signature verification
│       ├── appearance.go       # Visible signature rendering
│       ├── pkcs11/             # Hardware token support
│       ├── pkcs12/             # .p12/.pfx file support
│       └── nss/                # NSS database support
└── frontend/
    ├── src/                    # Web UI (vanilla JS + Tailwind)
    └── wailsjs/                # Auto-generated Wails bindings

Technology Stack

Component	Technology
Backend	Go 1.24
Desktop Framework	Wails v2
PDF Rendering	MuPDF (via go-fitz)
PDF Signing	digitorus/pdfsign
CLI Framework	Cobra
Logging	slog (structured)
Frontend	Vanilla JS + Tailwind CSS
Hardware Tokens	miekg/pkcs11

Configuration

Configuration is stored in ~/.config/lankir/:

File	Purpose
`config.json`	Application settings
`signature_profiles.json`	Saved signature profiles
`recent_files.json`	Recent files history

Configuration Options

{
  "theme": "dark",
  "accentColor": "#3b82f6",
  "defaultZoom": 100,
  "showLeftSidebar": true,
  "showRightSidebar": true,
  "defaultViewMode": "scroll",
  "recentFilesLength": 10,
  "certificateStores": [
    "/home/user/.certificates"
  ],
  "tokenLibraries": [
    "/usr/lib/x86_64-linux-gnu/opensc-pkcs11.so"
  ],
  "debugMode": false,
  "hardwareAccel": true
}

Hardware Token Support

Lankir supports PKCS#11 hardware tokens for enterprise-grade digital signatures:

Supported Tokens

Smart Cards (national ID cards, corporate cards)
USB Tokens (YubiKey, SafeNet, Feitian)
Hardware Security Modules (HSMs)

Configuration

Add your PKCS#11 module to the configuration:

lankir config set tokenLibraries '["/usr/lib/opensc-pkcs11.so"]'

Common module paths:

Distribution	OpenSC Module
Ubuntu/Debian	`/usr/lib/x86_64-linux-gnu/opensc-pkcs11.so`
Fedora/RHEL	`/usr/lib64/opensc-pkcs11.so`
Arch	`/usr/lib/opensc-pkcs11.so`

Troubleshooting

Common Issues

"No certificates found"

Check that certificate stores are configured: lankir config get certificateStores
For hardware tokens, ensure the token is inserted and drivers are installed
Verify PKCS#11 modules are accessible: lankir config get tokenLibraries

"Failed to open PDF"

Ensure the file exists and is readable
Check if the PDF is encrypted (password-protected PDFs not yet supported)

"Signature verification failed"

The PDF may have been modified after signing
Certificate may have expired or been revoked
Trust chain may not be complete

Debug Mode

Enable verbose logging for troubleshooting:

# GUI with debug logging
lankir --verbose gui

# CLI with JSON logging (for parsing)
lankir --json --verbose cert list

Contributing

Contributions are welcome! Please read our contributing guidelines before submitting PRs.

Development Workflow

Fork the repository
Create a feature branch: git checkout -b feature/amazing-feature
Make your changes
Run tests: task test
Commit your changes: git commit -m 'Add amazing feature'
Push to the branch: git push origin feature/amazing-feature
Open a Pull Request

Code Style

Go code follows standard gofmt formatting
Use meaningful variable and function names
Write tests for new functionality
Document exported functions and types

Support

If you find Lankir useful, consider supporting its development:

Cryptocurrency Donations

Bitcoin (BTC)

bc1q7utue52q2m66spl3prz3xxmmdw9varcupfa20f

Monero (XMR)

681AX96pcCFNbFs82MeQVR6W3pDCHRTHEGGHBMZiafLL

License

This project is licensed under the MIT License - see the LICENSE file for details.

MIT License

Copyright (c) 2025 Matbe34

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

Name		Name	Last commit message	Last commit date
Latest commit History 103 Commits
.github/workflows		.github/workflows
assets		assets
cmd/cli		cmd/cli
docs		docs
frontend		frontend
internal		internal
packaging		packaging
.gitignore		.gitignore
.readthedocs.yaml		.readthedocs.yaml
CHANGELOG-0.1.0.md		CHANGELOG-0.1.0.md
CHANGELOG.md		CHANGELOG.md
LICENSE		LICENSE
README.md		README.md
Taskfile.yml		Taskfile.yml
app.go		app.go
app_test.go		app_test.go
go.mod		go.mod
go.sum		go.sum
main.go		main.go
nfpm.yaml		nfpm.yaml
wails.json		wails.json

License

Matbe34/lankir

Folders and files

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Lankir

Overview

Key Highlights

Features

PDF Viewing & Operations

Digital Signatures

Certificate Management

Configuration

Installation

Option 1: Package Manager (Recommended)

Option 2: Download Package (.deb / .rpm)

Option 3: AppImage

Option 4: Static Binary

Usage

Launching the GUI

Using the CLI

Keyboard Shortcuts

CLI Reference

Global Flags

PDF Operations

Certificate Management

Digital Signatures

Configuration

Building

Prerequisites

Build Commands

Available Tasks

Architecture

Technology Stack

Configuration

Configuration Options

Hardware Token Support

Supported Tokens

Configuration

Troubleshooting

Common Issues

Debug Mode

Contributing

Development Workflow

Code Style

Support

Cryptocurrency Donations

License

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