Combine multiple lists into one unified set. Remove duplicates automatically and merge unique items from all sources.
Enter items one per line. The tool combines all unique entries automatically.
All unique items from both lists
List union combines items from multiple sources into one set without duplicates. This operation appears in data cleaning, inventory management, and content merging workflows. The tool processes each list, normalizes entries based on your settings, and outputs every unique item exactly once.
Union differs from intersection and difference. Intersection shows items present in all lists. Difference shows items in one list but not the other. Union shows every item from every list, removing duplicates automatically. This makes union ideal for merging customer databases, combining tag lists, or consolidating product catalogs.
Normalization options control how duplicates are detected. Case sensitive mode treats Apple and apple as different items. With case insensitive mode, they count as one. Trimming whitespace removes accidental spaces that create false duplicates. Empty line removal keeps results clean and focused.
Origin marking helps track where items came from. When enabled, results show [1] for items only in list one, [2] for items only in list two, and [1,2] for items appearing in both. This visibility supports data auditing and helps identify overlap between sources.
Sorting organizes results alphabetically for easier scanning. Unsorted output preserves the order items first appeared, which can help maintain priority or sequence from source lists. Choose sorting when you need alphabetical organization or skip it when order matters.
Practical applications include merging email lists from multiple campaigns, combining product SKUs from different vendors, consolidating tag collections from blog posts, and unifying customer databases after acquisitions. The tool handles thousands of items quickly and provides statistics showing how many duplicates were removed.
Each list is parsed line by line. Items are normalized based on your settings for case sensitivity and whitespace handling.
The tool compares normalized items across all lists. Duplicates are identified and removed, keeping only unique entries.
Unique items are combined into the final union. Optional sorting organizes results alphabetically for easier review.
Split input by line breaks, apply normalization rules, and filter empty entries based on your preferences.
Add items from each list to a unified collection, skipping duplicates based on normalized comparison.
Apply optional sorting, add origin markers if requested, and display the final combined list with statistics.
Combine customer databases, product catalogs, or inventory lists from multiple sources into one unified set.
Merge tag collections from blog posts, articles, or content items to create comprehensive tag libraries.
Remove duplicates from combined lists while preserving all unique entries for clean, organized datasets.
Common questions about combining lists and removing duplicates.
The tool compares items after applying your normalization settings. Items matching after case conversion and whitespace trimming are treated as duplicates. Only one instance appears in the final union result.
Union combines all unique items from all lists. Intersection shows only items that appear in every list. Use union when you want everything combined, intersection when you need common items only.
The current tool handles two lists at a time. For multiple lists, process them in pairs or use the merge multiple lists tool for batch processing.
Origin marking adds labels showing which list each item came from. [1] means only in list one, [2] means only in list two, [1,2] means in both lists. This helps track data sources and identify overlaps.
With sorting enabled, items are arranged alphabetically. Without sorting, items appear in the order they first appeared across all lists, preserving original sequence.
Order depends on sorting settings. Without sorting, items keep their first appearance order. With sorting enabled, results are alphabetical regardless of input order.
