Filter a list

The quickest method of list filtering

This tool scans a multiline list line-by-line and keeps or removes lines that match a pattern. Use plain text for simple substring matches or enable the RegEx checkbox to apply regular expressions for powerful, flexible filtering.

How to use

• Paste your list into the input area.
• Enter a pattern (plain text or regex).
• If needed, check the RegEx box to treat the pattern as a regular expression.
• Choose the filter mode: Leave matches (keep matching lines) or Remove matches (discard matching lines).
• Click Filter and copy the result.

Example usage

Extract ASUS models from a product list:

1. Pattern: ASUS (leave RegEx unchecked for a simple substring match).
2. Set filter type to Leave matches.
3. Click Filter.

Result: only lines that contain "ASUS" remain.

How the tool processes input

• Each input line is tested independently against the pattern.
• With RegEx enabled, the pattern is treated as a regular expression; without it, the tool performs a plain substring match.
• Use anchors (e.g., ^, $) and boundaries (e.g., \b) in regex mode to refine matches.
• For best results on lists, pre-clean the input (remove empty lines, de-duplicate) before filtering.

Examples & copyable regex patterns

• ^ASUS — lines starting with "ASUS".
• \b\d{4}\b — lines containing a 4-digit year (e.g., 2022).
• ^(?!.*refurb).* — exclude lines that contain "refurb" (negative lookahead).
• ^[^@]+@example\.com$ — match email addresses from example.com.
• ASUS (RegEx off) — simple substring match for "ASUS".

Tool chaining (workflows)

• Extract then filter: use Pattern Extractor to pull strings, then filter the extracted list to keep specific matches.
• Clean then filter: run Remove Empty Lines and Remove Duplicates first, then apply this filter for reliable results.
• Pre-process separators or punctuation with Remove Punctuation or Remove Non‑Alphanumeric Characters before filtering when patterns depend on character classes.

Tips & edge cases

• Test your regex on a small sample before running it on a very large list.
• If results are unexpected, try escaping special characters or toggling the RegEx checkbox to compare behavior.
• Use anchors (^, $) to avoid partial matches when you need exact-line matches.
• For bulk lists, consider de-duplicating (Remove Duplicates) after filtering.
• If you only need to remove lines containing a simple substring, consider Remove Lines Containing String for a quicker workflow.

FAQ

Does regex mode support case-insensitive searches?

The tool is case sensitive. If you need to make in non case sensitive - normalize case in a pre-step (convert the list to lowercase before filtering).

What regular-expression features can I use?

The RegEx checkbox lets you use standard regex constructs (anchors, character classes, quantifiers, groups, lookarounds). If a specific advanced feature is unsupported, test the pattern in the tool and adjust accordingly.

How are lines processed — can patterns match across lines?

Each line is evaluated independently. Patterns should be written to match a single line; multiline matches across line breaks are not applied unless the engine supports special flags — test your pattern on representative input.

Can I filter many strings at once?

Yes — paste a multiline list and run the filter. For best performance, remove empty lines (Remove Empty Lines) and duplicates (Remove Duplicates) beforehand when working with very large datasets.

What should I do if my pattern doesn't return expected results?

Verify whether RegEx is enabled, test a simpler pattern, escape special characters, and try anchors or word boundaries. Use small samples to iterate quickly before filtering the full list.

Related tools

• Pattern Extractor — find and extract strings that match a pattern.
• Remove Lines Containing String — remove lines with simple substring matches.
• Remove Empty Lines — clean blank lines before filtering.
• Remove Duplicates — de-duplicate results after filtering.
• Remove Non‑Alphanumeric Characters — normalize input when patterns depend on character sets.