Line Tools

Line Tools rolls three small, frequently-needed text jobs into one place: adding a prefix or suffix to every line of a list, filtering lines down to the ones that match (or don’t match) something, and repeating a line of text a set number of times. Instead of hunting down three separate single-purpose tools for what’s usually a thirty-second task, paste your text once, switch modes with a click, and copy the result. Everything processes locally in your browser — nothing you paste in is uploaded anywhere.

How to use Line Tools

1. Pick a mode — Add prefix/suffix, Filter lines, or Repeat text.
2. For Add prefix/suffix, paste your list into the input box and type what you want added to the start and/or end of every line — useful for turning a plain list into quoted strings, bullet points, or comma-separated values. A “skip blank lines” option keeps blank rows from picking up your prefix and suffix too.
3. For Filter lines, paste your text and enter a pattern to match against — plain text, or a regular expression for more precise matching. Choose whether to keep only the matching lines or remove them, and toggle case sensitivity as needed.
4. For Repeat text, type the line you want repeated and how many times, pick a separator (new line, comma, space, or your own custom one), and optionally append an incrementing number to each repetition.
5. Copy or download the result as a .txt file. You can also drag and drop a .txt or .csv file straight into the input instead of pasting, and your last input and settings are remembered the next time you open the tool.

Frequently asked questions

What’s the difference between the three modes?

Add prefix/suffix wraps every line with text you specify — handy for converting a plain list into a formatted one (quoted values, list items, SQL-ready strings, and similar). Filter lines keeps or removes lines based on whether they match a pattern, which is useful for pulling a subset out of a long paste — every line containing a certain word, for instance. Repeat text does the opposite of filtering: it generates many copies of a single line, which comes up when building test data or placeholder content.

Does the filter support regular expressions, or just plain text?

Both. Plain-text matching checks whether a line contains the text you typed, with an optional case-sensitivity toggle. Switching to regex mode lets you match more specific patterns — everything ending in a certain extension, lines starting with a number, and so on — for anyone comfortable with regex syntax.

Can I upload a file instead of pasting my text?

Yes — drag and drop a .txt or .csv file onto the input area (outside of Repeat text mode, which doesn’t need a bulk input) and it loads straight in.

Is my pasted text saved anywhere? It’s saved locally in your browser so your input and settings are still there if you come back to the tool later, but it’s never sent to a server or stored anywhere outside your device.

If what you need is closer to search-and-replace within your text rather than line-by-line filtering, Find and Replace covers that case, regex included. And if you’re checking a single line or paragraph for accidentally repeated words rather than repeated lines across a whole list, Duplicate Word Finder is built for exactly that.