Online Magic Number Detector for Clean Code
Scan code instantly with our free Magic Number Detector. Identify hard-coded values, improve code readability, and export constants directly in your browser.
About Magic Number Detector
The Magic Number Detector analyzes your source code to locate unexplained, hard-coded numeric literals. Magic numbers reduce readability and introduce bugs when values change across a codebase. This tool helps developers, code reviewers, and students quickly pinpoint values that should be refactored into named constants.
Everything runs client-side directly in your browser, ensuring your proprietary code remains secure and private. Paste your script to inspect logic, audit pull requests, and maintain clean coding standards without installing local static analysis packages.
Key features
- Scans source code instantly for hard-coded numeric values
- Filters out standard non-magic numbers like zero and one
- Displays line numbers and exact code context for matches
- Suggests named constant declarations to streamline refactoring
- Supports common languages including JavaScript, Python, and C++
- Runs completely in your browser for absolute code privacy
How to use Magic Number Detector
- Paste your source code into the text input area.
- Select your target programming language from the dropdown menu.
- Adjust detection settings to ignore standard values like 0, 1, or -1.
- Click the analyze button to find all undeclared numeric literals.
- Review flagged instances and copy suggested constant definitions.
Who is it for?
- Refactoring legacy software to replace hard-coded values with constants.
- Reviewing pull requests to enforce clean code and maintainability guidelines.
- Auditing math-heavy algorithms and business logic before production deployment.
- Teaching computer science students best practices for variable naming.
Frequently asked questions
What is a magic number in programming?
A magic number is a direct numeric literal used in code without explanation or context. Using named constants instead clarifies the purpose of the number and simplifies future updates.
Which numbers are excluded by the detector?
Common convention allows numbers like 0 and 1 for indexing or simple counters. You can configure the tool to ignore these baseline values and only flag arbitrary business logic numbers.
Is my source code uploaded to an external server?
No. The detector runs entirely in your browser using client-side JavaScript. Your code never leaves your device.
How should I fix a detected magic number?
Define a descriptive constant at the top of your file or in a dedicated configuration file, assign the numeric value to it, and replace all inline occurrences with that constant name.
Is this tool free to use?
Yes, the Magic Number Detector is completely free with no account or software installation required.