Text desk
Filter Lines
Keep only lines containing a literal piece of text, with an optional case-sensitive match.
Filter Lines: Extract only the lines containing a particular piece of text. Filter Lines searches for a literal substring anywhere in each entry and keeps matching lines in their original order. Choose case sensitivity when capitals matter; the result contains the complete lines rather than just the matched words. Runs 100% locally in your browser with zero server file uploads.
- Category
- Text tools
- Runs
- In your browser
- Cost
- Free · no sign-up
- Availability
- Ready to use
Runs entirely in your browser
Result
ReadyFiltering uses a literal contains check. Regular expressions and pattern execution are intentionally unsupported.
Contains predicate and sample selection
For query Q and line L, retain L when L contains Q; with case sensitivity off, compare the lowercase forms of both. Kept count is the number of lines satisfying that predicate. Input Batch 12\nDone 34\nBATCH 56\n with Q = batch and the toggle off gives Batch 12\nBATCH 56\n: two of three entries match. Turn the toggle on with the same lowercase query and none of these capitalised entries match. The original text is copied only after the decision.
Search conventions and long extracts
The Unicode Collation Algorithm (https://www.unicode.org/reports/tr10/) describes comparison conventions that a locale-aware search might use; this filter does not perform that kind of equivalence comparison or sorting. The query allows up to 200 code points. Source text is bounded at 100,000 code points and 10,000 logical lines. Input CRLF and bare CR become LF, and a final newline follows retained results when the input had one. For larger logs, filter separate chunks and concatenate the matches in their original chunk order. The editor also enforces its character allowance in UTF-16 units, so many emoji count as two input places. The regex tester can help develop a pattern for a separate pattern-capable workflow; that pattern is not accepted by this literal filter.
How to use it
- Paste or type your lines in the local editor.
- Set the options shown for this transformation and run it.
- Review the result, then copy or download the text.
Privacy & limitations
Your text and result stay on this device. There is no upload or execution of entered code.
Related tools
Frequently asked questions
Do dots, stars or brackets behave as search patterns?
No. A query such as a.b searches for that exact three-character sequence, and a star searches for a star. There are no wildcards, whole-word boundaries or regular expressions. A query consisting of spaces can be meaningful, but a completely empty query is rejected.
Does case-insensitive matching ignore accents or Unicode variants?
It compares lowercased text, rather than using language-specific collation. cafe does not match café, and composed é differs from e followed by a combining accent. German ß is not expanded into ss. Prepare normalised text separately when equivalent spellings should match.
Will matching several times repeat the same line?
No. Each logical line is checked once and either kept once or discarded. Repeated identical input lines are separate entries and can all survive. No matches produce empty output. Surviving entries retain their original case, padding and punctuation rather than the lowercased search form.
Free tool · runs in your browser · no account required