Line Filter

How to use

1. 1Paste your line-oriented text into the Input text box. Logs, lists, exports, source code, or anything where each line is a unit work.
2. 2Type one pattern per line into the Patterns box. Patterns can be plain substrings (default) or JavaScript regex when you switch the Pattern type.
3. 3Pick Keep matching or Remove matching under Action. Output updates instantly as you type.
4. 4Tune the Match rules: case sensitivity, whole-line match, trim before matching, skip blank lines, and optional line-number prefix.
5. 5Copy the filtered output or download it as a .txt file. Check the per-pattern hit counts at the bottom to confirm each rule did what you expected.

About this tool

Line Filter is a grep-style line filter that runs entirely in your browser. Paste any line-oriented text, type one pattern per line in the patterns box, and choose whether to keep the lines that match or remove them. Patterns can be plain substrings or full JavaScript regular expressions, and you can require any pattern to match (OR) or every pattern to match (AND). Toggle case sensitivity, switch to whole-line matching when you want the pattern to equal the entire line, trim leading and trailing whitespace before comparing, skip blank lines automatically, and optionally prefix every kept line with its original 1-based line number for traceability. A per-pattern hit counter shows how many lines each rule matched, and invalid regex patterns are flagged with the underlying error so a single bad rule never silently drops your output. Useful for triaging server logs, pulling specific entries out of CSV exports, cleaning email or domain lists, isolating TODO comments in source files, extracting only headings from a Markdown dump, or any task that would normally reach for grep, ripgrep, or a Find dialog. Everything stays on your device. There is no upload, no server processing, no rate limit, and no signup.

Free to use. Works in your browser. No signup, no login.