The "Remove Lines Containing Text" tool is a line filter that lets you keep exactly the lines you want from a block of text. You give it a keyword, a phrase, or a regular expression, and it either strips away every line that matches it or keeps only the lines that match it. The result is a clean, trimmed text list in seconds.

This is invaluable when you work with log files, lists, code, or any text where you need to drop or isolate a set of entries. Instead of deleting lines one by one, you paste your text, set your filter, and the tool decides which lines stay and which go - consistently and instantly.

I built this tool in plain JavaScript with no installs and no server. It splits your text into lines, checks each line against your filter (as a plain substring or a regular expression), and keeps or drops it based on the mode you choose. It then tells you how many lines and characters flowed in and out, so you can see exactly what changed. Everything runs locally in your browser, so your text never leaves your device.

The "Remove Lines Containing Text" tool goes through your text line by line. For every line it tests whether the line contains your filter text (or matches your regular expression), and then it keeps or drops the line according to the mode you picked.

The two modes are the mirror of each other. "Remove lines containing filter" deletes every line that matches and keeps the rest. "Remove lines NOT containing filter" does the opposite - it deletes everything that does not match and keeps only the matching lines. This second mode is the quickest way to pull out just the entries you care about.

You can search in a plain, literal way or switch on regular expressions for more control. Case sensitivity is optional, so you can choose whether "ERROR" should also catch "error". Because the whole thing runs in your browser, it is fast, free, and private - nothing is uploaded and nothing is stored.

Load an Example: Loads a sample list of lines into the input field so you can see the filter work straight away.

Upload a File: Uploads a text file from your local drive into the input field. Handy for filtering larger or saved files.

Filter Text: The word, phrase, or pattern each line is checked against. Leave it empty to keep every line.

Mode: Choose "Remove lines containing filter" to delete the matching lines, or "Remove lines NOT containing filter" to keep only the matching lines.

Regular Expression: When on, your filter is read as a regular expression, so you can anchor a match to the start (^ERROR) or end (done$) of a line, match digits ([0-9]+), or use any other pattern.

Case Sensitive: When off (default), the match ignores letter case, so "ERROR" matches "error" and "Error". When on, the match is exact.

Copy: Copies the filtered output to your clipboard so you can paste it anywhere.

Download: Downloads the filtered output as a text file.

Filter Lines: Press this button to filter the input and write the result to the output. This is the central action of the tool.

Clear: Empties both the input and output areas.

Reset: Clears the text areas and restores the default settings.

The "Remove Lines Containing Text" tool saves time whenever you need to thin out a list or pull out specific entries. It is especially useful for cleaning server logs, where you want to drop the routine lines and keep the warnings or errors. Here is an example of that scenario.

Example: You have an application log and want to drop every line that mentions "DEBUG" so only the meaningful lines remain.

Input:

INFO - Service started
DEBUG - loading config file
INFO - request received
DEBUG - cache miss
WARN - slow query detected

Output (Remove lines containing "DEBUG", case-insensitive):

INFO - Service started
INFO - request received
WARN - slow query detected

Here DEBUG matched the two debug lines, so they were dropped while the INFO and WARN lines stayed. The original order is preserved.

Another common use is pulling matching entries out of a mix - for example, keeping only the lines that contain an email address, or only the lines that start with a particular tag. You can also strip comment lines out of a code snippet by searching for a comment marker.

It is also a handy companion when tidying any list that came in with stray or unwanted rows, letting you remove noise in one click instead of hunting line by line.

FAQ 1: What does the "Remove Lines Containing Text" tool do?
Answer: The tool splits your text into lines and drops or keeps each line based on whether it contains your filter. You can remove the matching lines, or instead keep only the matching lines.

FAQ 2: What is the difference between the two modes?
Answer: "Remove lines containing filter" deletes every line that matches and keeps the rest. "Remove lines NOT containing filter" deletes every line that does not match and keeps only the matching lines.

FAQ 3: How do regular expressions help?
Answer: They let you match a pattern instead of a fixed string. For example, ^ERROR matches only lines that begin with "ERROR", and [0-9]+ matches any run of digits.

FAQ 4: What does "Case Sensitive" change?
Answer: When it is off, the match ignores letter case, so "ERROR" also finds "error" and "Error". When it is on, the match is exact and the two are treated differently.

FAQ 5: What happens if my regular expression is invalid?
Answer: If the pattern cannot be compiled, the tool shows a clear message and leaves the output unchanged. There is no need to worry - you can simply correct the pattern and try again.

FAQ 6: Is this tool free and do you save my text?
Answer: Yes, the tool is completely free. It runs entirely in your browser, so nothing is sent to a server and we do not store any of the text you type or upload.

FAQ 7: Is there a limit to how much text I can process?
Answer: You can paste or upload text as long as it remains within the tool's practical operating capacity. There is no fixed character limit set by the tool.