Link Checker

A fast and reliable link checker for markdown files and web pages written in Go.

Features

• ✅ Recursive scanning - Scan directories recursively for markdown files
• ✅ Direct URL checking - Check web pages directly for dead links
• ✅ Flexible ignore patterns - Ignore specific domains or regex patterns
• ✅ Configurable timeout - Set custom HTTP request timeouts
• ✅ Dead link filtering - Show only broken links
• ✅ Multiple output formats - Text and JSON output formats
• ✅ Detailed reporting - Shows source file, line numbers, and error details
• ✅ Mixed input support - Combine files, directories, and URLs in one command

Installation

go build -o linkchecker main.go

Usage

Basic Usage

# Check links in current directory
./linkchecker

# Check specific files
./linkchecker README.md docs/guide.md

# Check specific directory
./linkchecker ./docs

# Check web pages for dead links
./linkchecker https://example.com
./linkchecker https://github.com/user/repo

# Mixed usage - files and URLs
./linkchecker README.md https://example.com ./docs

Available Flags

Flag	Short	Description	Example
--recursive	-r	Recursively scan directories for markdown files	--recursive
--ignore		Comma-separated list of domains or regex patterns to ignore	--ignore="example.com,*.test.local"
--timeout		HTTP request timeout	--timeout=10s
--only-dead		Only show dead/broken links in output	--only-dead
--format		Output format: 'text' or 'json'	--format=json

Examples

Recursive scan with custom timeout

./linkchecker --recursive --timeout=10s ./docs

Check web page for dead links

./linkchecker https://example.com
./linkchecker --only-dead --format=json https://github.com/user/repo

Show only broken links in JSON format

./linkchecker --only-dead --format=json ./

Ignore specific domains

./linkchecker --ignore="example.com,localhost,*.test.local" ./docs

Check URL with custom settings

./linkchecker --ignore="ads.example.com,*.tracking.com" --timeout=10s https://mywebsite.com

Complex example with mixed inputs

./linkchecker \
  --recursive \
  --ignore="example.com,*.test.local" \
  --timeout=15s \
  --only-dead \
  --format=json \
  ./docs https://mysite.com README.md

Output Formats

Text Output (Default)

Link Checker Configuration:
  File Paths: [./docs]
  URLs to Check: [https://example.com]
  Recursive: true
  Timeout: 30s
  Only Dead Links: false
  Output Format: text

Link Check Results
==================

📄 Checking file: README.md
------------------------------------
✓ https://example.com
  Line: 10
  Status: 200

✗ https://broken-link.example
  Line: 25
  Status: 404
  Error: 404 Not Found

🌐 Checking web page: https://example.com
------------------------------------------
✓ https://external-link.com
  Status: 200

✗ https://dead-external-link.com
  Status: 404
  Error: 404 Not Found

Summary:
  Total Links: 5
  Valid: 2
  Invalid: 3
  Duration: 1.234s

JSON Output

{
  "summary": {
    "total": 2,
    "valid": 1,
    "invalid": 1,
    "duration": "1.234s"
  },
  "results": [
    {
      "url": "https://example.com",
      "status": "valid",
      "status_code": 200,
      "source": "README.md",
      "line": 10
    },
    {
      "url": "https://broken-link.example",
      "status": "invalid",
      "status_code": 404,
      "error": "404 Not Found",
      "source": "docs/guide.md",
      "line": 25
    }
  ]
}

Ignore Patterns

The --ignore flag supports both simple domain matching and regex patterns:

• Simple domains: example.com - matches any URL containing "example.com"
• Wildcards: *.test.local - matches any subdomain of test.local
• Regex patterns: Use full regex syntax for complex patterns

Examples:

# Ignore specific domains
--ignore="example.com,localhost"

# Ignore with wildcards
--ignore="*.test.local,*.example.org"

# Mix of patterns
--ignore="example.com,*.test.local,localhost:*"

Development

Project Structure

link-checker/
├── linkchecker/
│   ├── cli/          # CLI implementation
│   ├── parser/       # Markdown parsing logic
│   └── validator/    # Link validation logic
├── go.mod
├── go.sum
├── main.go
└── README.md

Building

go build -o linkchecker main.go

Testing

go test ./...

License

MIT License