Code Review Tool
Paste your code to get instant feedback on bugs, security vulnerabilities, performance issues, and code quality. Runs entirely in your browser.
Free Online Code Review Tool
This free code review tool analyzes your code instantly for bugs, security vulnerabilities, performance issues, and code quality problems. It supports JavaScript, TypeScript, Python, and other languages with smart pattern matching that catches real issues.
What does the code reviewer check?
- Bugs: Empty catch blocks, loose equality, unreachable code, accidental assignments in conditions
- Security: eval() usage, innerHTML XSS, SQL injection, hardcoded secrets, insecure HTTP, disabled SSL
- Performance: Deeply nested loops, array searches in loops, synchronous I/O, string concatenation in loops
- Code Quality: console.log left in, TODO comments, var usage, long lines, magic numbers, missing comments, high complexity
How is the quality score calculated?
Your code starts at a score of 100. Points are deducted for each issue found: errors cost 8 points, warnings cost 4, and informational issues cost 1 point. Additional penalties apply for excessive nesting depth and high cyclomatic complexity. The letter grade ranges from A (90-100) to F (below 60).
All analysis runs entirely in your browser — your code is never sent to any server. Private, fast, and free with 3 reviews per day.