Remove duplicates from the list

Remove duplicate lines online — Remove Duplicates from the list

Remove duplicate lines from any plain-text list. Choose case-sensitive or case-insensitive comparison, trim whitespace, and strip common prefixes/suffixes. The operation keeps the first matching line and reports how many duplicates were removed (counters appear below the editor).

How to use

• Paste your list into the editor.
• Open Remove → Duplicates.
• Pick options: case-sensitive or case-insensitive comparison, trim leading/trailing whitespace, and remove common prefixes/suffixes if needed.
• Apply the operation. The first occurrence of each unique line is kept; results replace the editor contents and counters appear below showing duplicates removed and remaining unique items.

Behavior & defaults

• First-match kept: when duplicates exist, the earliest (first) occurrence is preserved and later matches are removed.
• Default comparison: the tool is atomic and case-sensitive by default. To dedupe case-insensitively, convert text (Case Converter) or select the case-insensitive option if available.
• Whitespace handling: trimming is optional. If trimming is enabled, lines that differ only by leading/trailing spaces are treated as duplicates.
• Prefix/suffix removal: you can instruct the tool to ignore common prefixes or suffixes when comparing lines (useful for SKUs or numbered items).
• Reporting: after the run the tool shows counters below the editor — number of duplicates removed and number of unique lines remaining.

Examples

Example 1 — simple duplicate removal (first kept)

Input:
apple
banana
apple
orange
banana

Output:
apple
banana
orange

Example 2 — case-sensitive (default) vs case-insensitive

Input:
Apple
apple
APPLE

Default (case-sensitive) Output:
Apple
apple
APPLE

If you convert to lowercase first (Case Converter → lowercase) then remove duplicates:
apple

Example 3 — trimming whitespace

Input:
item1
 item1
item1 

If you enable trimming, Output:
item1

Example 4 — removing common prefixes

Input:
SKU:12345
SKU:12345
sku:12345

If you strip prefix "SKU:" and compare case-insensitively, Output:
12345
sku:12345  (depending on options chosen)

Build workflows — combine tools for real-world tasks

This tool is most powerful when used as a step in a short pipeline. A few practical workflows:

• Clean mailing lists: Paste CSV/lines → Remove Lines Containing (invalid rows) → Trim → Remove → Duplicates → copy results.
• Extract and dedupe URLs: URL Extractor → Append results to editor → Remove → Duplicates → Alphabetize List.
• Prepare unique SKUs: Remove Spaces → optional prefix/suffix strip → Remove → Duplicates.
• Generate unique test data: combine generators (Random String, Random Email) → Remove → Duplicates to ensure a unique sample set.
• Advanced filtering: Extract with Pattern Extractor, then dedupe, then export or convert to CSV/JSON via the editor area.

Tips & edge cases

• If you need case-insensitive dedupe, run Case Converter (lowercase) before removing duplicates.
• When working with CSV rows, consider normalizing columns first (Trim → Remove extra separators) so duplicate detection matches entire rows correctly.
• Prefix/suffix stripping is useful but be careful — stripping too broadly can merge distinct items. Test on a small sample before bulk operations.
• Results replace the editor content. Use the editor’s copy action to export or append results back into other workflows.

FAQ

Which duplicate is kept — the first or the last?

The first matching line is kept. Later duplicates are removed.

Is comparison case-sensitive by default?

Yes. The tool performs case-sensitive comparisons by default. To perform case-insensitive deduplication, convert text to a single case first or select the case-insensitive option if offered.

Does the tool trim whitespace when comparing lines?

Trimming is optional. Enable trimming to treat lines that differ only by leading/trailing spaces as duplicates.

Will I see how many duplicates were removed?

Yes. The tool displays counters below the editor after the operation showing how many duplicates were removed and how many unique lines remain.

Can I undo the operation?

The editor retains your previous content only if you use its undo/restore features. For safety, copy the original text to a separate buffer before bulk operations.

Related tools

• Trim — remove leading/trailing whitespace before deduplication.
• Remove Spaces — strip unwanted spaces inside lines.
• Remove Lines Containing — filter out unwanted rows before dedupe.
• Pattern Extractor — extract specific tokens prior to deduplication.
• Extract Unique Words — related extractor for unique-token workflows.
• Alphabetize List — sort after deduplication for easier review.