Remove Duplicate Lines
Remove repeated lines and keep only unique entries.
📘 How It Works
Line Parsing
Text is split on newline characters to create an array of individual lines. Each line is processed independently for duplicate detection.
Whitespace Normalization
When 'Trim whitespace' is enabled, leading and trailing spaces are removed from each line before comparison. This catches duplicates that differ only by spacing.
Set-Based Tracking
A JavaScript Set tracks seen lines. Sets provide O(1) lookup time, making duplicate detection fast even for large files with thousands of lines.
Case Sensitivity
When case-insensitive, lines are converted to lowercase for comparison only. The original casing is preserved in the output for the first occurrence.
Order Preservation
Lines are processed sequentially. The first occurrence is always kept; subsequent duplicates are discarded. This maintains document order.
💡 Common Use Cases
Email List Cleanup
Remove duplicate email addresses from mailing lists. Prevent sending multiple emails to the same recipient.
Log Deduplication
Clean server logs or error reports by removing repeated entries. Focus on unique events for debugging.
Data Import Preparation
Clean CSV or text data before importing to databases. Avoid duplicate key errors and data redundancy.
Keyword Lists
Deduplicate SEO keyword lists, product tags, or category names. Maintain clean taxonomies.
Code Cleanup
Remove duplicate import statements, configuration entries, or repeated lines in scripts.
Survey Response Processing
Identify unique responses from surveys by removing repeated answers for cleaner analysis.