AI can write code. Can it review code?

I tested five tools over three months. Here’s what works.

The Contenders

GitHub Copilot: $19/month CodeRabbit: $15/month Sourcery: $14/month (free for open source) Codium AI: Free tier available Amazon CodeWhisperer: Free tier available

Plus using Claude and ChatGPT directly via copy-paste.

What “AI Code Review” Actually Means

These tools do different things:

Automated PR comments: Bot reviews every pull request, leaves suggestions Inline suggestions: Improvements shown as you type Security scanning: Finding vulnerabilities Code quality: Style, patterns, best practices Bug detection: Finding logical errors

No tool does all of these well.

GitHub Copilot

Already paying for this as coding assistant. The review features are secondary.

What it does: Suggests improvements inline. Explains code on demand. Helps refactor.

What it doesn’t do: Automated PR review. Comprehensive security scanning.

Verdict: Great for development. Mediocre for review. But you probably have it anyway.

CodeRabbit

The most impressive automated reviewer.

What it does: Reviews every PR automatically. Leaves detailed comments. Explains potential issues. Suggests improvements.

What it catches: Logic errors, missing edge cases, security issues, performance problems.

What it misses: Context-dependent decisions. Business logic correctness.

Verdict: Best automated PR reviewer I tested. Worth $15/month if you do regular code review.

Sourcery

Focused on code quality and patterns.

What it does: Identifies refactoring opportunities. Suggests cleaner code. Enforces patterns.

What it catches: Duplicate code. Complex functions. Style inconsistencies.

What it misses: Bugs. Security issues. It’s about quality, not correctness.

Verdict: Nice to have, not essential. The suggestions are good but not critical.

Codium AI (now Qodo)

Free tier is generous.

What it does: Generates tests for your code. Suggests edge cases. Reviews PRs.

What it catches: Missing test coverage. Untested edge cases.

Verdict: Test generation is the killer feature. Actually useful. Free tier is enough for small teams.

Amazon CodeWhisperer

Free for individuals.

What it does: Similar to Copilot. Inline suggestions. Code completion.

What it catches: Basic issues as you type.

Verdict: Fine alternative to Copilot if you want free. Not as good, but acceptable.

What I Actually Use

Copilot for writing code: $19/month CodeRabbit for PR reviews: $15/month Codium for test generation: Free tier

Total: $34/month

Worth it? For a solo developer or small team, yes. The time savings exceed the cost.

The Limitations

No tool catches everything

AI finds certain patterns. It misses context. It doesn’t understand your business requirements.

False positives are annoying

Every tool flags things that aren’t problems. You learn to filter, but it’s overhead.

Not a replacement for human review

Junior developers still need senior review. AI catches syntax, not judgment.

My Recommendation

Start with Codium (free). See if AI test generation helps your workflow.

Add CodeRabbit ($15) if you do regular code review and want a first pass.

Copilot ($19) is worth it for writing code, not reviewing it.

Don’t buy multiple tools with overlapping features. Pick one per category.

And remember: AI review is a second opinion, not a final authority. Humans still make the decisions.