Drag files here or click to select
Supports .js .ts .py .java .c .cpp .cs .go .rs .php .rb .swift .kt .html .css .sql .sh .md etc.
Upload files or paste code to start counting
The Code Line Counter is an essential tool for developers. Here's a detailed guide on how to use it:
File Upload: Drag and drop code files into the upload area, or click to select files. The tool supports batch upload of multiple files and automatically recognizes file extensions to match the corresponding comment syntax. After uploading, click the "Analyze" button to see detailed statistics for each file. Supported formats include .js, .ts, .py, .java, .c, .cpp, .cs, .go, .rs, .php, .rb, .swift, .kt, .html, .css, .sql, .sh, .md, and other common programming and markup languages.
Paste Code: If uploading files is inconvenient, you can paste code directly into the text box. After pasting, select the corresponding programming language (or choose "Auto Detect"), then click the "Analyze" button. The tool will accurately count code lines, comment lines, and empty lines based on the selected language's comment syntax rules.
Interpreting Results: The statistics are divided into summary cards and a detailed table. Summary cards show the total lines, code lines, comment lines, and empty lines. The detailed table lists each file's statistics, including file name, language type, total lines, code lines, comment lines, empty lines, and code percentage (code lines as a percentage of total lines). Code percentage is an important indicator for assessing code quality—generally, a healthy range is between 50% and 80%.
The Code Line Counter plays an important role at various stages of software development:
Code Review & Metrics: During team code reviews, counting lines of code helps quickly understand project scale. Combined with the comment ratio, you can assess code maintainability and documentation level. A low comment rate may indicate code that's hard to understand and needs more comments; a high comment rate may indicate unclear code that relies too much on comments to explain logic.
Project Estimation & Scheduling: In agile development, Lines of Code (LOC) is an important reference for estimating effort and scheduling. While LOC doesn't directly represent development efficiency, combined with historical data, it helps teams estimate development time for new features or modules more accurately. Comparing LOC changes across different versions can also evaluate the effectiveness of refactoring.
Code Quality Assessment: Code line counting is one of the foundational metrics for code quality assessment. Combined with the empty line ratio, it can evaluate code cleanliness—appropriate empty lines improve readability, but too many may indicate loose code structure. The code percentage reflects code density; a low percentage may indicate redundant content in the file.
Comment Syntax Rules: Different programming languages have very different comment syntaxes. Single-line comments using // include JavaScript, Java, C++, C#, Go, Rust, PHP, Swift, Kotlin, etc.; using # include Python, Shell, Ruby, etc.; using -- includes SQL. Multi-line comments typically use /* */ or similar formats, while HTML uses <!-- -->. This tool automatically selects the corresponding comment syntax rules based on file extension.
LOC and Software Metrics: Lines of Code (LOC) is one of the most fundamental metrics in software measurement. Related metrics include SLOC (Source Lines of Code), LOC (total lines), and NCLOC (Non-Commented Lines of Code). More advanced metrics include Cyclomatic Complexity, Halstead Complexity, and Maintainability Index. Code line counting serves as the foundation for these advanced metrics.
Related Tools: Beyond line counting, developers can use code formatting tools (like Prettier, Black), code quality tools (like ESLint, SonarQube), and code coverage tools (like Istanbul, JaCoCo) to further improve code quality. Used together, these tools form a comprehensive code quality assurance system.
Supports JavaScript, TypeScript, Python, Java, C, C++, C#, Go, Rust, PHP, Ruby, Swift, Kotlin, HTML, CSS, SQL, Shell, Markdown, and other common programming languages. The tool automatically detects language type by file extension and counts according to the corresponding comment syntax.
No. This tool runs entirely in your browser. All code analysis and statistics are performed locally on your device. No data is ever uploaded to any server. You can even use it offline.
Empty lines contain only whitespace characters. Comment lines contain only comments (e.g., // comment, /* */ block comments). Code lines contain actual executable code, which may also include inline comments. If a line contains both code and comments, it is counted as a code line.
The reasonable range for code percentage (code lines / total lines) varies by project. Generally, 50%-80% is considered healthy. Too low may indicate too many empty lines or redundant comments; too high may indicate overly dense code with poor readability. The key is to maintain code clarity and maintainability rather than pursuing a specific percentage.
Yes. You can drag all code files from a project into the upload area, and the tool will count and aggregate results for each file. Note: Direct folder upload is not currently supported; you need to select multiple files. Future versions may support folder drag-and-drop.
Comment line counting only counts lines that are purely comments (like // comments). Code line counting counts lines that contain actual code. If a line contains both code and comments (like var x = 1; // initialize), it is counted as a code line rather than a comment line. This counting method better reflects actual code quality assessment needs.
There is theoretically no limit, but we recommend uploading no more than 100 files at a time to ensure browser performance. All file processing is done locally and does not consume network bandwidth.