Line Filter

📖 Tool Introduction

The Line Filter is a free online row-by-row filtering tool built for the kind of neat but noisy text that arrives one line per record: system logs, account lists, translation memory exports, compiler error dumps and plain-text exports of spreadsheets. You simply tell the tool what kind of lines you want, and it evaluates every line in turn, keeping the matches or sweeping them away. Three matching strategies are offered: contains-keyword, minimum-line-length and regular expression. Keyword mode is the simplest - type one word and every line containing it is selected. Minimum-length mode clears out blank lines, short comments and placeholder rows in one pass. Regex mode is the most powerful, and with anchors like caret, dollar and digit classes it can describe complex line formats precisely. Two processing modes are available: keep-matched outputs only the hits, which is perfect for fishing ERROR lines out of a log; drop-matched does the opposite, removing unwanted rows, which is handy for stripping blanks and comments. After every run, two coloured badges show exactly how many lines were kept and how many were dropped, so the effect is always measurable. All decisions happen locally in your browser, and no data is ever uploaded. A built-in example loads a realistic log snippet in one click, and the Ctrl+Enter shortcut runs the current rule without reaching for the mouse. Because the tool never sends a byte anywhere, it is safe to use with private server logs and internal ticket exports, and it stays responsive even when the source file contains tens of thousands of lines. The radio-based condition panel keeps every option visible at a glance, so you never hunt through nested menus just to swap from keyword mode to regex mode. Developers on call, support agents triaging tickets, and analysts slicing exported CSV rows all reach for this same tool, because it turns an otherwise manual eyeball scan into a one-click rule.

✨ Key Features

• Dual mode: keep matched lines or drop matched lines, both directions supported
• Three match rules: keyword contains, minimum length and regex, switchable instantly
• Live badges: kept and dropped line counts shown in colour, always measurable
• Case toggle: exact English letter-case matching when you need it
• Regex safety: an invalid pattern produces a clear error instead of silent filtering
• Fully local: pure in-browser processing, zero upload of logs or sensitive text

📝 How to Use

1. Choose the mode: keep matched lines or drop matched lines
2. Choose the match rule: keyword, minimum length or regex
3. Fill in the keyword, length threshold or regular expression in the field that appears
4. Paste the multi-line text you want to filter into the input area
5. Click Run Filter and read the output panel together with the kept/dropped badges

⚠️ Notes

• Empty input: running a filter with no text shows a friendly prompt
• Valid regex: an invalid pattern errors out instead of silently deleting data
• Keyword case: matching is case-insensitive by default; tick the box for exact case
• Blank lines: empty lines have length 0 and are removed at min length 1
• Original kept: results go to the output panel so you can retune and retry