When Simple Search Isn't Enough
You're looking at a text file with 500,000 lines. You need to find entries that contain "error" AND "database" but NOT "timeout". Your text editor's find function isn't going to cut it. Neither is scrolling for hours.
That's exactly why we built this list filter. It handles complex conditional logic that regular search tools can't touch. Combine multiple criteria, use boolean operators, enable regex when you need pattern matching—all while processing files at speeds your desktop apps would envy.
How to Filter Your Data
Here's the straightforward workflow:
- Paste your text or upload a file containing your data
- Enter your search terms (one per line for multiple conditions)
- Select AND or OR logic based on your matching needs
- Toggle case sensitivity and regex mode as needed
- Click filter and download or copy your results
Understanding Boolean Logic
AND Logic: All Conditions Must Match
When you select AND, every term you enter must appear in a line for it to pass through. Think of it as setting a higher bar:
- Terms: 'error', 'critical' → Only lines containing both words
- Terms: '2024', 'January', 'sale' → Lines mentioning all three concepts
- Terms: 'user123', '@gmail.com' → Specific user with specific domain
OR Logic: Any Condition Can Match
OR logic casts a wider net. A line passes if it matches any single term:
- Terms: 'error', 'warning', 'critical' → All severity levels
- Terms: '.jpg', '.png', '.gif' → Any image file extension
- Terms: 'New York', 'Los Angeles', 'Chicago' → Multiple cities
Power User Features
Regular Expression Mode
Enable regex mode when plain text matching isn't precise enough. Common patterns we see users apply:
^2024-— Lines starting with dates from 2024\\b[A-Z]{2,5}\\b— Uppercase acronyms (2-5 letters)\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}— IP addresseshttps?://[^\\s]+— URLs (http or https)\\$\\d+\\.\\d{2}— Price formats like $19.99
Exclude Mode: Filter Out Instead of In
Sometimes it's easier to specify what you don't want. Exclude mode inverts your filter—lines matching your criteria get removed instead of kept. This works well for:
- Removing log entries at certain severity levels
- Filtering out test data from production records
- Excluding specific domains or IP ranges
- Removing blank lines or formatting artifacts
Real-World Filtering Scenarios
Log File Analysis
You're debugging a production issue. Your log file has millions of entries. You need errors from the authentication service in the last hour. Combine timestamp patterns with service identifiers and error keywords. What would take hours of manual review happens in seconds.
Data Cleaning for Import
You're preparing a CSV for database import. Some rows have invalid data—missing fields, malformed entries, test records. Use exclude mode with patterns that match problematic rows. Your import file comes out clean and ready.
Research and Content Mining
You've scraped thousands of pages. You need entries mentioning specific topics, from specific time periods, excluding certain sources. Layer your filters to drill down to exactly the content you need for your research.
Combining with Other Tools
Our list filter works well in combination with other Mooflair tools:
- Before filtering: Use Remove Duplicate Lines to clean your source data
- After filtering: Run results through Reposition to rearrange columns
- Email-specific: For email extraction, try our dedicated Email Filter Tool with domain filtering
Performance Tips
Processing happens entirely in your browser. Here's how to get the best performance:
- Keep your browser tab in focus—background tabs may throttle processing
- For extremely large files (10M+ lines), consider splitting and processing in batches
- Simple string matches run faster than complex regex patterns
- AND logic typically processes faster than OR with many terms
We've tested this tool with files containing tens of millions of lines. Your browser can handle more than you might expect.
Frequently Asked Questions
What's the difference between AND and OR logic in filtering?
AND logic requires all conditions to match—a line must contain every term you specify. OR logic keeps lines matching any of your terms. Use AND when you need precise matches, OR when you want broader results. Most complex filtering tasks combine both.
How do I use regex patterns in this tool?
Enable the regex mode toggle, then enter standard JavaScript regular expressions. For example, ^Error matches lines starting with 'Error', [0-9]{3} matches any three consecutive digits, and user@.+\.com matches email patterns. Remember to escape special characters like dots and brackets.
Can I filter out lines instead of keeping matches?
Yes. Use the exclude mode to remove lines that match your criteria instead of keeping them. This is useful when you want to clean data by removing unwanted entries rather than selecting specific ones.
Why is case sensitivity important for filtering?
Case sensitivity determines whether 'Error' matches 'error' or 'ERROR'. Disable case sensitivity for broader matching when capitalization varies in your data. Keep it enabled when you need precise matches, like distinguishing between variables in code.
How large of a file can this tool process?
Our tool handles files with millions of lines. Processing happens in your browser using chunked reading, so file size is limited only by your available system memory. For extremely large datasets, consider splitting files or using our progressive loading feature.