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About Add Line Numbers
Add Line Numbers — free, private, browser-based text tool
Number every line — 1, 2, 3 — with custom format and padding. It runs in your browser, so the file is processed on your own device.
Why use Add Line Numbers
- ·Files stay on your device — nothing is uploaded
- ·No signup needed
- ·Works in any modern browser, on any OS
- ·Free daily use; Pro removes limits and watermarks
How to use it
- 1Drop a text file on the page, or click to choose one.
- 2Pick the options you want.
- 3Copy or save the result.
What Add Line Numbers does
Number every line — 1, 2, 3 — with custom format and padding.
How it works
Native browser performance via TextDecoder streams; regex execution uses the engine's optimized matcher; no payload size limits. The processing code runs inside the page, so your file is not uploaded to a server — you can confirm this in your browser's DevTools → Network tab.
Frequently asked questions
Does Add Line Numbers upload my files?+
No. Add Line Numbers runs in your browser and processes the file on your device. Nothing is sent to our servers.
Is Add Line Numbers free?+
Yes, with a daily free allowance and no signup. Xonvert Pro ($4.99/month) removes the daily limits and the watermark on exported files.
Do I need to install anything?+
No. It works in any modern browser on Windows, macOS, Linux, ChromeOS, Android and iPad.
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