Code quality, bugs, and security —
explained with real examples.

What is LearnCodeGuide?

An AI code analysis tool that finds bugs, security issues, and quality problems — what it is and who it is for.

What is Double Check?

How a second, independent AI model verifies your code analysis for higher confidence.

AI Code Review in GitHub Actions

Set up automated AI review on every pull request with a workflow file and an API key secret.

How to Find Bugs in Code

Manual review, static analysis, AI tools, and tests — how to combine them for maximum bug coverage.

How to Explain Code with AI

Use AI to understand legacy code, unfamiliar patterns, and complex algorithms in plain English.

How to Refactor Code with AI

Use AI to simplify, restructure, and improve code quality — with practical before/after examples.

Security Code Analysis

SAST tools, OWASP Top 10, and AI analysis — how to find security vulnerabilities before they ship.

How to Improve Code Quality

Practical techniques for cleaner, more maintainable code — with tools, checklists, and metrics.

How to Review Code Faster

Strategies and tools to speed up code review without missing important bugs or security issues.

AI Code Review for Beginners

What AI code review is, how it works, and how to use it if you are just starting out.

AI Code Review for Students

How students can use AI code review to debug assignments and write better code faster.

Free Code Review Tools

A comparison of the best free tools for automated and AI-assisted code review in 2025.

LearnCodeGuide vs ChatGPT

Structured code analysis vs open-ended chat — which approach gives better results and why.

Code Review Checklist for Beginners

A practical checklist for reviewing code: what to look for in bugs, security, and style.

Code Smells — Examples & Fixes

Real code smell examples — long methods, duplicate code, magic numbers — and how to fix them.

SQL Injection — Code Examples

How SQL injection works, real vulnerable code examples, and the correct parameterized query fix.

Path Traversal — Examples & Prevention

What path traversal is, how attackers exploit it, and how to safely validate file paths.

JavaScript Code Review Guide

A structured approach to reviewing JavaScript code for bugs, security, and quality.

Common JavaScript Bugs

The most common JavaScript bugs — null errors, type coercion, async mistakes, and more.

JavaScript Bug Detector

How to detect bugs in JavaScript code using AI, linters, and static analysis tools.

JavaScript Undefined Errors

Cannot read properties of undefined — why it happens, how to debug it, and how to prevent it.

JavaScript Async/Await Mistakes

Common async/await bugs: missing await, unhandled rejections, and race conditions.

JavaScript Callback Hell

What callback hell is, why it is a problem, and how to refactor to async/await.

JavaScript Closure Bugs

How closures cause bugs in loops, event handlers, and async code — with fixes.

JavaScript Equality Operator Bugs

== vs === in JavaScript — why loose equality causes bugs and when to use each.

JavaScript Hoisting Bugs

How JavaScript hoisting causes bugs with var, function declarations, and the TDZ.

JavaScript 'this' Context Bugs

'this' is undefined or wrong — arrow functions vs regular functions explained with fixes.

JavaScript Long Function

Why long functions are a problem and how to break them into smaller, testable pieces.

JavaScript Magic Numbers

What magic numbers are in JavaScript and how to replace them with named constants.

JavaScript Dead Code

How to identify and remove dead code in JavaScript to reduce complexity and bundle size.

JavaScript Duplicate Code

How to detect and refactor duplicate code in JavaScript with real before/after examples.

JavaScript XSS

Cross-site scripting in JavaScript — how it happens, real examples, and prevention.

JavaScript SQL Injection

SQL injection via Node.js — vulnerable patterns and parameterized query fixes.

JavaScript CSRF

Cross-site request forgery in JavaScript apps — how it works and CSRF token protection.

JavaScript Security Checklist

A security checklist for JavaScript code: XSS, CSRF, injection, auth, and dependency risks.

TypeScript Code Review Guide

How to review TypeScript code — type safety, strict mode, common patterns to check.

TypeScript 'any' Type Abuse

Why using 'any' defeats type safety and how to replace it with proper types.

TypeScript Type Errors

Common TypeScript type errors, what they mean, and how to fix them without using 'any'.

TypeScript Null & Undefined Errors

Strict null checks, optional chaining, and how to handle null safely in TypeScript.

TypeScript Async Type Errors

Type errors in async TypeScript code — Promise types, return types, and await issues.

TypeScript Generic Type Bugs

Bugs from incorrect generic types in TypeScript functions, classes, and interfaces.

TypeScript Dead Code

How to find and remove unreachable code, unused exports, and dead types in TypeScript.

TypeScript Hardcoded Secrets

Why hardcoded secrets in TypeScript are dangerous and how to use environment variables instead.

TypeScript Interface vs Type

interface vs type in TypeScript — key differences and when to use each one.

TypeScript Security Mistakes

Common security mistakes in TypeScript: unsafe casting, prototype pollution, XSS.

TypeScript SQL Injection

SQL injection risks in TypeScript/Node.js and how parameterized queries prevent them.

TypeScript Strict Mode Errors

Common errors when enabling TypeScript strict mode and how to fix them systematically.

TypeScript XSS

XSS vulnerabilities in TypeScript and React apps — how they occur and how to prevent them.

Python Code Review Guide

A structured guide to reviewing Python code for bugs, security, and quality issues.

Common Python Bugs

The most common Python bugs — NoneType errors, index errors, mutable defaults, and more.

How to Detect Python Bugs

How to detect bugs in Python code using AI, linters (Pylint, Flake8), and testing.

Python NoneType Error

AttributeError: 'NoneType' object has no attribute — why it happens and how to fix it.

Python Index Out of Range

IndexError: list index out of range — common causes and fixes in Python.

Python Async/Await Mistakes

Common async/await bugs in Python: missing await, event loop errors, blocking calls.

Python Infinite Loop

How infinite loops occur in Python and how to detect, debug, and prevent them.

Python Mutable Default Argument

Why [] and {} as function defaults cause shared state bugs — and the correct fix.

Python Long Function

Why long Python functions are a problem and practical refactoring techniques.

Python Dead Code

How to find and remove dead code in Python — unused functions, unreachable branches.

Python Global Variable Abuse

Why global variables in Python cause bugs and how to refactor them with proper scope.

Python Unused Imports

How unused imports in Python slow down code and how to detect and remove them.

Python SQL Injection

SQL injection in Python — vulnerable patterns and parameterized fixes with psycopg2/SQLAlchemy.

Python XSS

XSS vulnerabilities in Python web apps (Flask, Django) and how to prevent them.

Python Command Injection

Command injection via subprocess and os.system in Python — how to prevent it.

Python Path Traversal

Path traversal attacks in Python — how they happen and how to validate file paths safely.

Python Hardcoded Secrets

Why hardcoded secrets in Python are dangerous and how to use os.environ and .env files.

Python Security Mistakes

Common Python security mistakes: hardcoded secrets, SQL injection, weak crypto, and more.

Java Code Review Guide

A structured guide to reviewing Java code for bugs, security vulnerabilities, and design issues.

Java NullPointerException

NullPointerException — common causes, how to debug it, and Optional as a prevention strategy.

Java ArrayIndexOutOfBoundsException

Why this exception happens and how to fix array access bugs in Java.

Java String Comparison Bugs

String == vs .equals() in Java — why == fails for string comparison and how to fix it.

Java Long Method

Why long methods in Java are a problem and how to refactor with extract method patterns.

Java Dead Code

How to identify and remove dead code in Java — unused methods, unreachable blocks, old APIs.

Java Duplicate Code

Duplicate code in Java — how to detect it and refactor with inheritance or utilities.

Java Magic Numbers

What magic numbers are in Java and how to replace them with named constants or enums.

Java SQL Injection

SQL injection in Java — PreparedStatement misuse and correct parameterized query patterns.

Java XSS

Cross-site scripting in Java web apps (Spring, Servlets) and how to prevent it.

Java Command Injection

Command injection in Java via Runtime.exec() — how it works and how to prevent it.

Java Security Checklist

A security review checklist for Java code: injection, auth, crypto, access control, and more.