Number Lines
Add a number in front of each line of multi-line text. Set the start number and separator, and skip blank lines if you like. Handy for organizing lists, scripts, and code — all processing happens inside your browser, so your text is never sent externally.
How to use
- Enter or paste the text to number, one item per line, in the input box.
- Choose the start number, separator, and whether to skip blank lines.
- Click "Number lines", then copy the text in the result box with "Copy result".
Frequently asked questions
Can I change the start number?
Yes. Set the start number to any value, and numbering begins there and increases by 1 for each line.
Are blank lines numbered too?
When "Skip blank lines" is on, blank lines are left as is without a number. When off, blank lines are numbered too.
Is the text I enter sent to a server?
No. All processing happens inside your browser, and your text is never sent to any external server.
Practical example and verification criteria
Number Lines: First determine whether the conversion deletes or replaces source text, only changes order, or creates a new notation; check line endings, whitespace, case, Unicode, and language-specific rules. For hard-to-reverse operations such as replace or sort, preserve a separate source copy and test the option's scope on a small sample.
Number Lines: For a quick check, start with A\nB → 1 A\n2 B as a small input whose result relationship you can verify directly. Confirm that the input summary, units, and options match your intent before applying the tool to real values or a copy of the source; this reduces setup mistakes.
Number Lines: Compare line and item counts, first and last values, duplicates, and blank lines before and after conversion; when possible, reverse the conversion to see whether the source is recovered. Initial consonants, Roman numerals, slugs, and hashtags can have different allowed characters or meanings by language and platform, so match the actual target system's rules.
Number Lines · Work record: For real work, record the input conditions, selected options, and result together. Do not assume the same state will remain after a refresh or device change. Preserve important results separately using copy, download, a screenshot, or another method the page supports, then reopen them in the target environment.
Number Lines · Error check: If an error or unexpected result appears, reduce the input, run again with default options, and then change one condition at a time. Recording error messages and boundary values helps distinguish format issues, unsupported cases, and browser resource limits, and prevents an empty result from being mistaken for success.
Number Lines · Scope of use: Check the page guidance for browser processing versus server lookup, storage location, and supported scope. Use sensitive source material or secrets only when strictly necessary. High-impact work such as legal, financial, or medical decisions or changes to an operational system requires current authoritative information and a separate verification process.