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Add sequential line numbers to text for reference and debugging. Free online line number adder for code and document formatting.
Line Number Adder is a free online text tool that works right in your browser — whatever you enter is processed locally and never sent to a server. No installation, no signup; works on both phone and desktop, ready to use instantly.
Text tools support large file processing — files over 1MB automatically use Web Workers for smooth, non-blocking operation. Encoding detection and batch operations included.
We noticed many online text tools send your content to remote servers for processing. Since privacy is our core principle, we built this tool to handle everything locally — your text stays on your device.
Data entry clerks and operations staff processing lists from customers, vendors, or internal forms. Instead of scrolling through rows and fixing each one by hand, paste the whole batch here and apply the same change to every line instantly.
Yes, completely free with no signup required.
Yes, it works on mobile browsers with touch support.
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For very large text (over 1MB), tools use Web Workers for background processing, so the UI stays responsive.
ToolPure supports UTF-8, UTF-16, ASCII, and Base64 encoding/decoding. The tools also support URL encoding, HTML entity encoding, and hex encoding for special characters.
The text tools can handle documents up to 5MB in size (approximately 5 million characters). Word count, character count, and line count update in real-time as you type or paste content.
Yes, the find and replace tool supports full regex syntax including capture groups, lookahead, and lookbehind. You can also perform case-sensitive or case-insensitive replacements with match highlighting.
Yes. Line Number Adder is a pure front-end tool: whatever you type or paste is processed only in your browser's memory and never sent to a server. It disappears as soon as you refresh or close the page.
🔒 Privacy & Security：All processing happens locally in your browser. Files are never uploaded or stored.
🔒 Privacy: All processing happens locally in your browser. Your files and data never leave your device — no upload, no server, no tracking.