How to Use Claude Code for Code Reviews

Get thorough code reviews in minutes. Learn how to set up Claude Code for automated review workflows that catch bugs, security issues, and style problems before they ship.

Claude Code reviews your code by scanning diffs, branches, or pull requests for security vulnerabilities, performance issues, logic bugs, and style problems — then gives you actionable feedback with line references and suggested fixes, all in minutes instead of hours. It uses Claude Opus 4.6's 200K token context window to analyze entire changesets at once, so human reviewers can focus on architecture and business logic.

With hooks for automated review pipelines and subagents for parallel analysis, Claude Code supports everything from quick one-off reviews to reusable review skills your whole team can share. This guide walks you through setting it all up.

What Is a Claude Code Review?

A Claude Code review is AI-assisted analysis of your code changes. You point Claude at modified files, a branch, or a pull request, and it examines the code for:

• Security vulnerabilities - SQL injection, XSS, authentication flaws, exposed secrets
• Performance issues - N+1 queries, memory leaks, inefficient algorithms
• Logic bugs - Off-by-one errors, null reference risks, race conditions
• Error handling - Missing try/catch, unhandled edge cases, silent failures
• Code style - Naming conventions, formatting, documentation gaps
• Test coverage - Missing tests, untested edge cases

Claude provides actionable feedback with specific line references and suggested fixes. You decide which suggestions to implement.

Setting Up Your Review Workflow

There are several ways to review code with Claude Code. Choose the workflow that fits your process:

Review @src/auth/login.js and @src/auth/session.js for
security issues and bugs

Review all changes on this branch compared to main.
Focus on security, performance, and code style.

Review PR #142. Check for security issues, performance
problems, and whether the tests cover the changes.

Review my staged changes (git diff --staged).
Any issues I should fix before committing?

Effective Review Prompts

The quality of your review depends on how you ask. Here are prompts for different review focuses:

Review @src/api/payments.js with security as the top priority.

Check for:
- SQL injection vulnerabilities
- Authentication and authorization gaps
- Sensitive data exposure in logs or responses
- Input validation issues
- Insecure cryptographic practices

For each issue, explain the risk and show how to fix it.

Review @src/services/reports.js for performance issues.

Look for:
- N+1 query patterns
- Missing database indexes (based on query patterns)
- Unnecessary loops or redundant operations
- Memory leaks or large object retention
- Opportunities for caching

Estimate the impact of each issue (minor/moderate/severe).

Do a thorough code review of the changes on this branch.

Organize findings by severity:
- Critical: Security holes, data loss risks, crashes
- High: Bugs that will affect users
- Medium: Performance issues, poor error handling
- Low: Style issues, documentation gaps

For each finding, include the file, line number, issue
description, and suggested fix.

Review this code as if mentoring a junior developer.

For each issue:
1. Explain what's wrong
2. Explain WHY it's a problem (not just that it is)
3. Show the better approach
4. Link to relevant documentation or best practices

Be encouraging but thorough.

Creating a Code Review Skill

Instead of typing review instructions each time, create a reusable review command. This ensures consistent reviews and makes it easy for your whole team to use.

Step 1: Create the Command File

Create .claude/commands/review.md in your project:

# Code Review

Review the specified files or branch for issues.

## Security Checklist
- [ ] No SQL injection (parameterized queries used)
- [ ] No XSS (output properly escaped)
- [ ] Authentication checked before sensitive operations
- [ ] Authorization verified (user can access resource)
- [ ] No secrets in code or logs
- [ ] Input validation on all user data

## Performance Checklist
- [ ] No N+1 queries
- [ ] Large datasets paginated
- [ ] Expensive operations cached where appropriate
- [ ] No blocking operations in async code

## Code Quality Checklist
- [ ] Error handling covers edge cases
- [ ] Functions are single-purpose and testable
- [ ] Variable names are descriptive
- [ ] Complex logic is commented
- [ ] No dead code or debug statements

## Output Format
Organize findings as:

### Critical Issues
(security vulnerabilities, data loss risks)

### Bugs
(logic errors, crashes, incorrect behavior)

### Performance
(slow queries, inefficient code)

### Suggestions
(style, readability, maintainability)

For each issue include:
- File and line number
- Description of the problem
- Suggested fix with code example

Step 2: Use the Command

Now you can run consistent reviews with one command:

/project:review @src/api/users.js

Or review a whole directory:

/project:review the changes on feature/user-auth branch

What to Look For in Reviews

Here is what Claude checks by category:

Using Hooks for Automated Reviews

Claude Code 2.1+ introduced hooks — custom shell commands that run at specific lifecycle events. You can use hooks to automatically review all AI-generated code before it's written to disk, creating a fast feedback loop that catches quality issues early.

PostToolUse Hook for Review

Set up a PostToolUse hook that triggers after Claude writes a file, checking the output against your standards:

# In your .claude/settings.json, add a hook:
{
  "hooks": {
    "PostToolUse": [{
      "tool": "write_file",
      "command": "your-linter $FILE_PATH"
    }]
  }
}

This ensures that every file Claude writes passes your linter automatically. If it fails, Claude sees the error and can fix the issue before moving on.

Using Subagents for Parallel Reviews

For large PRs, Claude Code can spawn subagents to review different aspects in parallel. One subagent checks security, another checks performance, and a third checks code style — all simultaneously. This dramatically speeds up comprehensive reviews.

Review this PR using parallel analysis:
- Security audit of all auth-related changes
- Performance review of database queries
- Style and documentation check
Run these checks simultaneously and compile findings.

Team Workflow Tips

Here is how teams get the most value from Claude Code reviews:

Use Claude as First Reviewer

Before requesting human review, run Claude's review and fix the obvious issues. This respects your colleagues' time and leads to more productive review discussions.

# Before opening a PR
/project:review my changes on this branch

# Fix issues Claude found, then
git add . && git commit -m "Address review feedback"

# Now open PR for human review

Create Project-Specific Review Commands

Different projects have different concerns. Create specialized review commands:

• .claude/commands/review-api.md - Focus on REST conventions, validation, auth
• .claude/commands/review-frontend.md - Focus on accessibility, performance, UX
• .claude/commands/review-data.md - Focus on schema changes, migrations, integrity

Review Your Own Code First

Before committing, have Claude review your staged changes:

Review my staged changes. Any issues before I commit?

This catches typos, forgotten debug statements, and obvious bugs before they enter version control.

Automate PR Reviews

For teams using GitHub, you can script Claude to review PRs. Claude Code integrates with the GitHub CLI and can read PR diffs directly:

# In your PR workflow or locally
claude -p "Review PR #$PR_NUMBER. Focus on security and
check if tests cover the changes. Output as markdown
suitable for a PR comment."

You can also use MCP integrations to connect Claude Code to your GitHub repository, allowing it to access PR details, comments, and CI status without manual setup.

IDE-Based Reviews

With Claude Code's VS Code and JetBrains extensions, you can trigger reviews directly from your editor. The extension provides inline diffs, @-mentions for specific files, and conversation history — making it easy to review changes without leaving your IDE.

Common Mistakes

FAQ

Can Claude Code review code in any language?

Claude reviews code in most popular languages including JavaScript, TypeScript, Python, Java, C#, Go, Ruby, PHP, Rust, and others. It understands language-specific security issues and idioms.

How do I handle false positives?

If Claude flags something incorrectly, explain why it is not an issue. Over time, add these explanations to your CLAUDE.md so Claude learns your conventions. You can also add "This is intentional because X" comments in the code.

Should I use Plan Mode for code reviews?

Plan Mode is useful for reviewing complex changes where you want Claude to analyze the full scope before providing feedback. For routine reviews, Normal Mode works fine.

Can Claude fix the issues it finds?

Yes. After Claude identifies issues, you can ask it to fix them: "Fix the SQL injection vulnerability in line 42" or "Apply all the style fixes you suggested." Review each fix before approving.

How does Claude Code compare to tools like SonarQube?

Static analysis tools like SonarQube check syntax rules and patterns. Claude understands context, can explain issues in plain English, suggests fixes, and catches logical issues that rule-based tools miss. Use both for comprehensive coverage.

Can I use hooks to auto-review all AI-generated code?

Yes. Claude Code's hooks system lets you run custom scripts at lifecycle events like PostToolUse. You can set up a hook that runs your linter or custom review script every time Claude writes a file, catching issues before they enter your codebase. This creates an automated quality gate for all AI-generated code.

Does Claude Code work with my IDE for reviews?

Yes. Claude Code has extensions for VS Code, JetBrains, Cursor, and Windsurf. The extensions provide inline diffs, @-mentions for referencing files, plan review, and conversation history directly in your editor. You can trigger reviews from the IDE instead of the terminal.

Related Guides

• Debug Code with Claude Code — fix bugs Claude's reviews catch
• Slash Commands in Claude Code — create custom review commands
• CLAUDE.md File Guide — set project context for better reviews
• Claude Code Prompts and Examples — more prompt patterns
• What Is Claude Code? — the fundamentals