List Comparator & Processor

Quick Start

1. Paste your first list into the List A text area.
2. Paste your second list into the List B text area.
3. Choose your desired Comparison Mode.
4. Click the Compare Lists button.

Core Features

• Data Input: You can either paste your data directly into the text areas or use the Choose File button to load data from a .txt or .csv file. The tool will use pasted text if available, otherwise it will check for a file.
• Adding & Removing Lists: Click the + Add Another List button to add more lists (up to a maximum of 4). For lists C and D, a × button will appear in the top-right to remove them.
• Running a Comparison: The main blue Compare Lists button runs the comparison on all active lists using the currently selected global options.

Comparison Modes Explained

The available modes change depending on the number of lists.

When comparing 2 lists:

• In Both (A ∩ B): Shows items that exist in both List A and List B.
• All Distinct (A ∪ B): Merges both lists and shows every unique item from them combined.
• Only in B (B – A): Shows items that are in List B but are not in List A.
• Only in A (A – B): Shows items that are in List A but are not in List B.
• Unique to each (A ∆ B): Shows items that are in either A or B, but not in both.

When comparing 3 or 4 lists:

• Intersection (In ALL lists): Shows only the items that exist in every single list.
• Union (All distinct items): Merges all lists and shows every unique item from them combined.

Data Cleaning & Processing

• Pre-processing Options: These global options clean the data before comparison.
  • Trim Whitespace: Removes spaces from the beginning and end of each line. (Default: On)
  • Remove Empty Lines: Filters out any blank lines. (Default: On)
  • Remove Duplicate Lines: De-duplicates each list individually before comparison. Respects the 'Case Sensitive' setting. (Default: Off)
• Per-List Find & Replace: Each list has its own Find/Replace tool. Enter text in the Find... and Replace With... fields and click the gray Apply button for that list to perform the transformation. Check Use Regex to use Regular Expressions.
• Global Find & Replace: In List A's options, check the Apply to All Lists box. When you click List A's Apply button, the operation will be performed on all active lists. This hides the other Find/Replace sections to show it's in global mode.

Advanced Features

• CSV Column Selection: If you upload a .csv file with multiple columns, a dropdown will appear allowing you to select which column's data to use for the comparison.
• Enhanced Results (for 2 Lists only): When comparing two lists, the results section provides extra detail. The statistics box shows counts for unique items, and a Venn Diagram gives a quick visual summary. A Diff View tab also appears, showing a merged list with added lines in green (+) and removed lines in red (-).

Program Limitations

• Text Area Size: Pasting extremely large lists (over 200 KB) into the text boxes may cause browser slowdowns. For very large datasets, using the file upload is recommended.
• List Limit: The tool supports a maximum of 4 lists to ensure a clean layout and stable performance.

Created by Sinisa Bozic

Suggestions and comments are appreciated!