y509

y509

y509 is a TUI tool designed to make analyzing and validating X.509 certificate chains painless. Built with Go, Bubble Tea, and Lip Gloss.

Features

• Performance First: Powered by a custom viewport rendering engine. Handles thousands of certificates smoothly with O(n) complexity.
• Popup UI: Intuitive modal-driven search and filtering. No more complex command-line flags for basic tasks.
• Smart Validation: Validates individual certificates against the entire loaded pool. Automatically detects trust anchors.
• Deep Search: Instant search across Subject, Issuer, and SANs (DNS names).
• Themeable: Fully customizable colors via YAML. Ships with a beautiful "Catppuccin" inspired default.
• 🏁 Zebra Striping: Clean, alternating row colors for perfect readability in long lists.
• Multi-Source: Read from files, directories, or pipe directly from stdin.

Installation

macOS / Linux (Homebrew)

brew tap kanywst/y509 https://github.com/kanywst/y509
brew install y509

Go (Version 1.25+)

go install github.com/kanywst/y509@latest

Usage

Quick Start

# Open a certificate file
y509 cert-chain.pem

# Pipe from OpenSSL or other tools
openssl s_client -connect example.com:443 -showcerts | y509

# Run with debug logging
y509 --debug certs.pem

Keyboard Controls

Configuration

y509 looks for a configuration file at ~/.y509.yaml.

theme:
  text: "252"
  border: "240"
  border_focus: "62"
  status_bar: "62"
  status_bar_text: "230"
  highlight: "62"
  highlight_text: "230"
  highlight_dim: "238"
  list_row_alt: "235" # Zebra striping color
  status_valid: "40"
  status_warning: "220"
  status_expired: "196"
  title: "aqua"

Development

We use Go 1.25+ tools.

make build      # Build with version info
make test       # Run test suite
make lint       # Run golangci-lint (via go tool)
make vulncheck  # Run govulncheck (via go tool)

Contributing

Contributions are welcome! Please feel free to submit a Pull Request. For major changes, please open an issue first to discuss what you would like to change.

1. Fork the Project
2. Create your Feature Branch (git checkout -b feature/AmazingFeature)
3. Commit your Changes (git commit -m 'Add some AmazingFeature')
4. Push to the Branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

License

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