AI Code Improver (Free Tool)
AI-powered code improvement for Python, JavaScript, Java, C++, and 100+ languages. Modernize syntax, refactor complex logic, optimize performance, and apply best practices. Transform legacy code into clean, maintainable code.
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Issue Description
Hint: Describe what you want to build or paste your code, select target language, and click Generate.
How It Works
- 1
Paste Your Code
Copy legacy code, outdated syntax, or suboptimal implementations from any source. Supports functions, classes, modules, entire files from Python, JavaScript, Java, C++, and 100+ programming languages.
- 2
AI Analyzes Improvement Opportunities
Advanced AI identifies outdated patterns, inefficient algorithms, poor naming, code smells, missing error handling, duplication, and violations of SOLID principles and language-specific best practices.
- 3
Receive Improved Code
Get modernized code with latest syntax standards, refactored logic, optimized algorithms, better variable names, comprehensive error handling, and applied design patterns while preserving original functionality.
Legacy vs Modern Code
| Feature | Legacy Code | Improved Code |
|---|---|---|
| Syntax | Legacy/Outdated | Modern Standards |
| Readability | Complex/Unclear | Clean/Maintainable |
| Performance | Unoptimized | Optimized Algorithms |
| Best Practices | Ignored | Applied Consistently |
| Error Handling | Missing/Basic | Comprehensive Checks |
| Maintainability | Hard to Update | Easy to Modify |
Examples
Example 1: Modernizing JavaScript Code
var data = [];
function fetchData(callback) {
var xhr = new XMLHttpRequest();
xhr.open('GET', '/api/users');
xhr.onload = function() {
if (xhr.status === 200) {
data = JSON.parse(xhr.responseText);
callback(null, data);
} else {
callback(new Error('Failed'));
}
};
xhr.send();
}const data = [];
const fetchData = async () => {
try {
const response = await fetch('/api/users');
if (!response.ok) {
throw new Error(`HTTP error! status: ${response.status}`);
}
const users = await response.json();
return users;
} catch (error) {
console.error('Failed to fetch users:', error);
throw error;
}
};Key Changes:
The AI modernized legacy XMLHttpRequest callback pattern to modern async/await with fetch API. Changed var to const for immutability, converted callback-based function to Promise-based async function, added proper error handling with try-catch, improved error messages with status codes, and applied ES6+ syntax. This eliminates callback hell, improves readability, uses standard fetch API, and follows modern JavaScript best practices. The refactored code is easier to test, debug, and maintain.
Example 2: Refactoring Python Code
def process(items):
result = []
for i in range(len(items)):
if items[i] % 2 == 0:
result.append(items[i] * 2)
total = 0
for item in result:
total = total + item
return totaldef process_even_numbers(numbers: list[int]) -> int:
"""
Calculate sum of doubled even numbers.
Args:
numbers: List of integers to process
Returns:
Sum of all even numbers multiplied by 2
"""
return sum(num * 2 for num in numbers if num % 2 == 0)Key Changes:
The AI applied multiple Python best practices: renamed function to descriptive 'process_even_numbers', added type hints (list[int] -> int), included comprehensive docstring following Google style, replaced verbose for loops with list comprehension, eliminated temporary result array using generator expression, combined filtering and mapping in single expression, and reduced 8 lines to 1 clean expression. Performance improved from O(n) space complexity to O(1), code became more Pythonic following PEP 8, and readability increased significantly. The refactored code is easier to understand, test, and maintain while being more efficient.
Frequently Asked Questions
The AI applies multiple improvements: modernizes syntax (ES6+, latest features), refactors complex logic into clean functions, optimizes algorithms, improves variable naming, adds error handling, removes code duplication, applies SOLID principles, uses design patterns, enhances type safety, and follows language-specific best practices like PEP 8 for Python or Airbnb style for JavaScript.
No. The AI preserves functionality while improving quality. It refactors implementation without changing behavior. Improvements include better variable names, cleaner structure, modern syntax, performance optimizations, and best practice patterns. Always test improved code, especially edge cases, to ensure compatibility with your specific environment and dependencies.
Yes. The AI specializes in modernizing legacy code by converting deprecated syntax to current standards, replacing old patterns with modern alternatives, updating library usage, refactoring callback hell to async/await, converting var to const/let, updating class syntax, applying functional programming patterns, and ensuring compatibility with latest language versions while maintaining backward compatibility where needed.