Paste any text or list, type the words you want to filter by, and this free tool either removes every line containing those words or keeps only the lines that contain them. Multiple filter words work together, matching ignores capital letters unless you say otherwise, and a whole-word option stops "cat" from matching "catalog". No sign-up, and your text never leaves your browser.
Line Filter Tool
Remove lines containing a word — or keep only the lines that do.
What Is a Line Filter Tool?
Developers do this job with a terminal command called grep. Everyone else ends up scrolling a long list and copying out the lines they want, one at a time. A line filter tool is grep for the rest of us: paste your lines, say which words matter, and get back either only the matching lines or everything except the matching lines — instantly, in your browser.
It works on anything line-shaped: server logs, keyword lists, URL lists, email exports, CSV rows pasted as text, product lists, code, survey answers — if it is one item per line, it can be filtered.
How to Use This Tool (Step by Step)
- Paste your text into the Input box — one item per line.
- Type your filter words, one per line. A line counts as matching if it contains any of your words (this is an OR filter:
errorortest). - Choose the mode: Remove lines containing throws the matches away and keeps the rest; Keep only lines containing does the opposite.
- Set the options if you need them (explained below — most people only ever need whole-word).
- Click Filter Lines, check the count, then copy or download the output.
The Two Modes, With an Example
Say your log has 6 lines and your filter word is error:
| Mode | You get |
|---|---|
| Keep only lines containing "error" | Just the problem lines — the 2 ERROR entries (matching ignores capital letters by default). |
| Remove lines containing "error" | The other 4 lines — the clean log with the errors stripped out. |
Same word, opposite jobs. "Keep" is for extracting what you care about; "Remove" is for cleaning what you don't.
Options That Save You From Wrong Results
Match case (off by default). By default error matches ERROR, Error and error alike — usually what you want. Turn Match case on when capitals carry meaning, for example separating the log level Error from the word "error" inside a message.
Whole word only. A plain contains-test is generous: filtering for cat also catches catalog, category and delicate. Whole-word matching requires the word to stand alone, so cat matches "my cat sleeps" but not "catalog". If a filter ever returns surprising lines, this option is the usual fix.
Remove empty lines. Pasted exports love blank lines. Keep this on and they never reach your output.
Read the count. The tool always reports "X of Y lines kept". That number is your sanity check: kept far more than expected, your word is too broad (try whole-word); kept nothing, check the spelling — or switch Match case off.
Common Jobs This Tool Does
| Job | Mode & words |
|---|---|
| Pull every error out of a server log | Keep only · error (add a date or timeout as a second word to widen the net) |
| Strip test rows from a customer export | Remove · test with Whole word on, so real names containing "test" survive |
| Get only the /blog/ URLs from a big URL list | Keep only · /blog/ |
| Remove every address from one email domain | Remove · @competitor.com |
| Clean a keyword list of a topic you dropped | Remove · the topic word (one run per topic, or several words at once) |
| Extract one user's activity from an app log | Keep only · their user ID |
Frequently Asked Questions
If I enter several filter words, must a line contain all of them?
No — any one of them is enough (OR logic). A line containing error or test matches when both words are listed. To require two words in the same line, filter twice: run the output of the first filter through a second one.
Is matching case-sensitive?
Not by default — Error, ERROR and error all match each other, which is what most people want. Tick "Match case" only when capitals themselves matter.
What does "whole word" actually change?
It requires your word to stand alone, bordered by spaces, punctuation, or the line's edges — instead of appearing anywhere inside a longer word. It is the fix for classic surprises like cat matching catalog.
Can it handle big files?
Yes for everyday sizes — tens of thousands of lines filter instantly, and a few hundred thousand is fine on a normal computer. For million-line logs, a terminal tool like grep is genuinely the better instrument; this page is for the 99% of jobs below that.
What happens to blank lines?
With "Remove empty lines" on (the default), blank and spaces-only lines never appear in the output. Turn it off if your format needs them preserved.
Is my text uploaded anywhere?
No. Filtering runs entirely in your browser with JavaScript; your text is never sent, logged, or stored. That also makes the tool safe for logs and exports you would not paste into a random server.
Is this tool free?
Yes — completely free, no sign-up, no install.
Last updated: November 2026. Companion tools: the Bulk URL Opener for opening lists of links, and the Bulk Google Search Tool for opening keyword searches in bulk.
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