Best Free Tools to Review AI-Generated Code Before You Ship

Why AI-Generated Code Needs a Different Kind of Review

Traditional code review tools were built for code written by humans. They catch syntax errors, style violations, and known vulnerability patterns. That works when a developer writes 50 lines a day and understands every line.

AI-generated code is different. Cursor, Bolt, Lovable, and Claude Code produce hundreds of files in a single session. The code compiles, the app runs, but underneath there are patterns that traditional tools were never designed to catch:

• Packages imported that do not actually exist on npm (hallucinated imports)
• API routes with no authentication middleware
• Secrets hardcoded directly in frontend code
• God files with 500+ lines handling multiple responsibilities
• Test files that exist but contain zero assertions
• Mixed async patterns that cause subtle race conditions

A free tool that only checks for ESLint violations will miss all of these. You need tools that understand the specific failure modes of AI-generated code.

The Free Tools Compared

1. VibeDoctor - The Platform Built for Vibe-Coded Apps

VibeDoctor is the only code review platform designed specifically for AI-generated code. It runs 129+ automated checks across 15 diagnostic areas and produces a scored report with prioritized findings and fix suggestions.

What makes it different

Most tools focus on one area - Snyk does dependencies, ESLint does style, GitHub does secrets. VibeDoctor runs all of these in a single scan and adds checks that no other tool performs:

• Hallucinated import detection - finds npm packages your AI tool invented that do not actually exist. If an attacker registers that name, your app installs malicious code.
• Vibe coding health checks - patterns specific to AI-generated code like god files, empty test bodies, mixed async patterns, and missing error handling.
• Full-stack scanning - scans both your codebase (security, quality, dependencies) and your live URL (performance, SEO, SSL, headers, broken links) in one pass.
• Vitals Score - a single 0-100 score so you know where your app stands overall, not just a list of individual findings.
• Code structure analysis - Vibe X-Ray maps your codebase into modules, files, symbols, and dependencies so you can understand what your AI actually built.

Free tier

1 scan per day, no credit card required. Each scan produces a full diagnostic report with every finding, severity level, affected file, and a suggested fix. The free tier does not limit which checks run - you get the complete 129+ check battery on every scan.

Best for

Solo founders and small teams who want a single tool that covers everything. If you are only going to use one tool from this list, this is the one that covers the most ground for AI-generated code.

2. npm audit - Dependency Vulnerability Scanning

npm audit is built into npm and scans your package-lock.json for known CVEs (Common Vulnerabilities and Exposures). It is free, fast, and already installed on your machine.

What it catches

• Known security vulnerabilities in your npm dependencies
• Vulnerabilities in transitive dependencies (packages your packages depend on)
• Severity levels (critical, high, moderate, low)

What it misses

• Everything outside of npm dependencies - no code quality, no security patterns, no performance analysis
• Hallucinated imports (it checks existing packages, not missing ones)
• Vulnerabilities in your own code (it only checks third-party packages)

How to use it

Run npm audit in your project directory. For automatic fixes where a patched version exists, run npm audit fix. For a production-only check, run npm audit --omit=dev.

Best for

A quick dependency health check that takes 5 seconds. Use it alongside a broader tool like VibeDoctor, not as your only review step.

3. ESLint - Code Style and Basic Quality

ESLint is the standard JavaScript/TypeScript linter. It catches style violations, unused variables, unreachable code, and basic quality issues. Most AI-generated projects include an ESLint config, though the AI often disables the strictest rules.

What it catches

• Unused variables and imports
• Unreachable code after return statements
• Missing semicolons, incorrect indentation (style rules)
• Basic type issues with TypeScript plugin
• React-specific rules (missing keys, hooks violations) with React plugin

What it misses

• Security vulnerabilities (SQL injection, XSS, hardcoded secrets)
• Performance issues (N+1 queries, blocking I/O)
• Dependency vulnerabilities
• AI-specific patterns (hallucinated imports, god files)
• Anything outside JavaScript/TypeScript files

How to use it

Run npx eslint . in your project. If the AI-generated project does not include an ESLint config, run npm init @eslint/config to create one. For stricter checking, enable the @typescript-eslint/strict preset.

Best for

Catching basic code quality issues and enforcing a consistent style. Essential but not sufficient on its own - it only covers one narrow slice of what can go wrong in AI-generated code.

4. GitHub Code Scanning - Secrets and CodeQL

GitHub provides two free scanning features: secret scanning (detects committed credentials) and CodeQL (static analysis for known vulnerability patterns). Both are available for public repositories.

What it catches

• Committed API keys, tokens, and credentials (secret scanning)
• Common vulnerability patterns via CodeQL (SQL injection, path traversal, etc.)
• Dependency alerts via Dependabot

What it misses

• Private repos (free tier only covers public repos for CodeQL)
• AI-specific code patterns
• Performance analysis
• Live URL scanning (SEO, SSL, headers)
• Code organization issues (god files, complexity)

How to use it

Enable it in your GitHub repository settings under "Code security and analysis." Secret scanning runs automatically. CodeQL requires a GitHub Actions workflow.

Best for

Catching committed secrets in public repos. If your vibe-coded project is on a public GitHub repository, enable this immediately - it is free and automatic.

5. Snyk - Dependency Security

Snyk scans your project dependencies for known vulnerabilities and license issues. It supports npm, pip, Maven, Go modules, and other package managers.

What it catches

• Known CVEs in direct and transitive dependencies
• License compliance issues
• Container image vulnerabilities (Docker)
• Infrastructure-as-code misconfigurations

What it misses

• Vulnerabilities in your application code (only checks dependencies)
• AI-specific patterns
• Code quality, performance, or frontend issues
• Live URL analysis

Free tier limitations

Snyk's free tier includes a limited number of tests per month. For solo developers running occasional checks, this is usually enough. For continuous monitoring, you need a paid plan.

Best for

Deep dependency analysis with remediation advice. Overlaps significantly with npm audit but provides more detail and supports more languages.

The Recommended Stack for Vibe-Coded Apps

No single tool catches everything. Here is the combination that provides the best coverage for free:

1. VibeDoctor (primary) - Run a full scan after every coding session. Covers security, dependencies, code quality, AI patterns, performance, and live URL analysis in one pass. 1 free scan per day.
2. ESLint (continuous) - Keep it running in your editor for real-time style and basic quality feedback as you work.
3. npm audit (before deploy) - Quick dependency check before every deployment. Takes 5 seconds.
4. GitHub secret scanning (always on) - Enable it once and forget it. Catches committed secrets automatically.

This stack costs nothing and covers security vulnerabilities, dependency CVEs, code quality, AI-specific patterns, performance, and committed secrets. The key is that VibeDoctor fills the gaps that the other tools leave open - the AI-specific checks, the full-stack analysis, and the unified score that tells you where you stand.

What to Look for in Your First Scan

When you run your first code review on an AI-generated project, focus on these categories in order of priority:

1. Critical security findings - hardcoded secrets, SQL injection, exposed API keys. Fix these before anything else.
2. Dependency vulnerabilities - known CVEs with available patches. Run npm audit fix for quick wins.
3. Hallucinated imports - packages that do not exist on npm. Remove them and replace with real alternatives.
4. Missing authentication - API routes without auth middleware. Add authentication before going live.
5. Performance issues - N+1 queries, blocking I/O, excessive bundle size. These affect user experience.

Everything else - code style, TODO comments, test coverage - matters but can wait until the critical issues are resolved.

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