Claude Code Hooks — Custom Automation Recipes

Hook Types

Popular Recipes

Auto-Format on Write

{
  "hooks": {
    "PostToolUse": [
      {
        "matcher": "Write|Edit",
        "command": "npx biome check --write $CLAUDE_FILE_PATH 2>/dev/null || npx prettier --write $CLAUDE_FILE_PATH 2>/dev/null || true"
      }
    ]
  }
}

Run Tests After Code Changes

{
  "hooks": {
    "PostToolUse": [
      {
        "matcher": "Write|Edit",
        "command": "if echo $CLAUDE_FILE_PATH | grep -q '\\.test\\.'; then npx jest $CLAUDE_FILE_PATH --no-coverage 2>&1 | tail -5; fi"
      }
    ]
  }
}

Lint Python Files

{
  "hooks": {
    "PostToolUse": [
      {
        "matcher": "Write|Edit",
        "command": "if echo $CLAUDE_FILE_PATH | grep -q '\\.py$'; then ruff check --fix $CLAUDE_FILE_PATH 2>/dev/null; fi"
      }
    ]
  }
}

Block Sensitive File Edits

{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Write|Edit",
        "command": "if echo $CLAUDE_FILE_PATH | grep -qE '\\.(env|pem|key)$'; then echo 'BLOCKED: Cannot edit sensitive files' >&2; exit 1; fi"
      }
    ]
  }
}

Slack Notification on Task Complete

{
  "hooks": {
    "Stop": [
      {
        "command": "curl -s -X POST $SLACK_WEBHOOK -d '{\"text\":\"Claude Code finished a task in '$(basename $(pwd))'\"}'  2>/dev/null || true"
      }
    ]
  }
}

Auto-Commit After Changes

{
  "hooks": {
    "Stop": [
      {
        "command": "if [ -n \"$(git diff --name-only)\" ]; then git add -A && git commit -m 'wip: Claude Code auto-save' --no-verify 2>/dev/null; fi"
      }
    ]
  }
}

Type Check TypeScript

{
  "hooks": {
    "PostToolUse": [
      {
        "matcher": "Write|Edit",
        "command": "if echo $CLAUDE_FILE_PATH | grep -q '\\.tsx\\?$'; then npx tsc --noEmit 2>&1 | head -20; fi"
      }
    ]
  }
}

Security Scan

{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Bash",
        "command": "if echo $CLAUDE_TOOL_INPUT | grep -qiE 'rm -rf|curl.*\\|.*sh|wget.*\\|.*bash'; then echo 'BLOCKED: Potentially dangerous command' >&2; exit 1; fi"
      }
    ]
  }
}

Key Stats

• 20+ ready-to-use recipes
• 4 hook event types
• Pattern matching with regex
• Environment variables available
• Community-maintained

FAQ

Q: What are Claude Code Hooks? A: Shell commands that run automatically before or after Claude Code tool uses — like auto-formatting after every file write, or blocking edits to sensitive files.

Q: Can hooks block Claude Code actions? A: Yes, PreToolUse hooks can return exit code 1 to block the action.

Q: Do hooks slow down Claude Code? A: Hooks run synchronously, so keep them fast (<1 second). Use background processes for slow operations.