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Duplicate List Item Finder

World's Simplest List Tool

This is a super simple browser-based application that finds duplicate items in a list. If an item appears in a list more than once, then the program will print it in the output area. Depending on the output mode, it can print each duplicate one time or as many times as they are repeated. You can also skip all empty items and remove surrounding whitespaces. Created by list geeks from team Browserling.

᠎᠎᠎          Tool Options

Item Boundaries

Select this option if the item
boundary is a symbol or multiple
symbols. (Enter symbols below.)
Select this option if the item
boundary is different symbols
or patterns. (Enter regex below.)
Enter item boundary symbol
or regex. For example, "," or /-{1,2}/.

Duplicate Search Settings

Output each duplicate item
only once.
Output all repeated copies
of items.
For example, for the input list
"a, a, a, b, b, c", the first mode
will print "a, b", and the second
mode will print "a, a, b".
If items have a different case,
then they are consider as
different items.

Output Separator and Trimming

Use this symbol to separate
items in the duplicate list.
Delete all leading and trailing
whitespaces from the list items.
Ignore all items that
have zero length.

What Is a Duplicate List Item Finder?

With this utility, you can find repeated items in any list. The program runs through all items in the input list and checks if the current item has been seen before. Duplicate items that appear in the list more than once are returned to the screen. By default, each duplicate item is returned to the screen only once. For example, if the input list is "a, b, a, a, c, c", then the output list is "a, c". You can change the duplicate report mode and display all item copies on the screen. In this case, the output for the list "a, b, a, a, c, c" will be "a, a, c". By default, lowercase, uppercase, or mixed-case items are considered to be the same. For example, "Apple", "apple", and "aPPLe" are treated as repeating items. If you want such items to be considered unique, then enable the "Case-sensitive Items" option. The input items can be numbers, words, strings, symbols, and other glyphs. To correctly find item boundaries in a list, you can use the option for separating items by a character or a regular expression. Just select the split format that your list uses and enter the character or regular expression in the item boundary delimiter field. To get a consistent and well-formatted list in the output, you can set a constant separator for the output list of duplicates. By default, the trim items option is also enabled. This option controls the spaces at the beginning and end of items. If two items differ only by spaces at the beginning or end, then they are considered to be equal items. And another option that's enabled controls empty items. If an item has zero length then it's considered to be an empty item and is not displayed in the output. Listabulous!


Duplicate List Item Finder Examples

Click to try!

List of Clothes

In this example, we find duplicate clothes in a shopping list. Each garment that has been listed more than once is displayed on the screen. To skip displaying empty items, we have activated the "Remove Empty Items" option. The other option "Trim List Items" is activated as well. As the input list of clothes is comma-separated, we use a single character boundary mode to extract the items and set the boundary character to a comma. In the output, we print each item on a new line, using the character "\n" as a separator.

jacket, scarf ,, coat, skirt, pants,, shirt , dress, hat, socks, pants, dress, shirt, , coat, suit, socks, jeans, hat, slacks, hat, jeans, jeans
pants dress shirt coat socks hat jeans
Required options
These options will be used automatically if you select this example.
Select this option if the item
boundary is a symbol or multiple
symbols. (Enter symbols below.)
Enter item boundary symbol
or regex. For example, "," or /-{1,2}/.
Output each duplicate item
only once.
If items have a different case,
then they are consider as
different items.
Use this symbol to separate
items in the duplicate list.
Delete all leading and trailing
whitespaces from the list items.
Ignore all items that
have zero length.

Case-sensitive Items

In this example, we take inventory of goods in a warehouse. Each product has its own unique code consisting of letters and digits, and it can only exist in the warehouse in one copy. Unfortunately, the data list was filled by an inattentive worker and he added several goods to the list twice. To find the duplicate product codes, we load the list of codes as the input, and in the output, we find all the duplicate items. We also activate the "Case-sensitive Items" option, as codes with uppercase and lowercase letters (such as "8pmh7" and "8PmH7") correspond to different products.

"0tKL9" "6RJb1" "8pmh7" "8PmH7" "9TdN3" "3pR9h" "1sGZ2" "2jBV5" "7mC0r" "6pH8f" "5nK2t" "9dJ1s" "8nL2d" "7rL3g" "8bP6h" "9mT0n" "6jZ1s" "7mC0r" "2hK5g" "1tN7b" "3pR9h" "8nL2d" "2HK5G" "8nL2d" "7jH5t" "9mP0f"
"7mC0r" "3pR9h" "8nL2d" "8nL2d"
Required options
These options will be used automatically if you select this example.
Select this option if the item
boundary is a symbol or multiple
symbols. (Enter symbols below.)
Enter item boundary symbol
or regex. For example, "," or /-{1,2}/.
Output all repeated copies
of items.
If items have a different case,
then they are consider as
different items.
Use this symbol to separate
items in the duplicate list.
Delete all leading and trailing
whitespaces from the list items.
Ignore all items that
have zero length.

List of Control Characters

This example finds and extracts all repeating items in a list of ASCII control characters. Since the input list has the TSV format (tab-separated values), we use the regular expression "/\s/" to separate items by tabs and accidental spaces. The program displays all repeating control characters exactly as many times as they repeat and separates them with a space character.

NUL NUL SOH STX ETX ETX ETX EOT ENQ ENQ ENQ ENQ ACK BEL BS BS BS TAB TAB TAB LF VT FF FF CR SO SI SI DEL DLE DC1 DC1 DC1 DC2 DC3 DC4 DC4 NAK SYN SYN ETB CAN EM EM SUB SUB SUB ESC ESC FS GS RS RS US
NUL ETX ETX ENQ ENQ ENQ BS BS TAB TAB FF SI DC1 DC1 DC4 SYN EM SUB SUB ESC RS
Required options
These options will be used automatically if you select this example.
Select this option if the item
boundary is different symbols
or patterns. (Enter regex below.)
Enter item boundary symbol
or regex. For example, "," or /-{1,2}/.
Output all repeated copies
of items.
If items have a different case,
then they are consider as
different items.
Use this symbol to separate
items in the duplicate list.
Delete all leading and trailing
whitespaces from the list items.
Ignore all items that
have zero length.

List of Banknote Glyphs

The list in this example is made from banknote symbols and the delimiter character is a tilde. To find duplicate list elements, we first split the input data by the tilde character via the "Boundary is a Symbol" mode. Then we clean up all spaces that surround the banknotes via the "Trim List Items" option. We find the unique banknote duplicates and print them in a new semicolon character-separated list.

€ ~ ¥ ~ ₹ ~ ₽ ~ € ~ € ~ £ ~ ₩ ~ ฿ ~ ฿ ~ £ ~ ฿ ~ $ ~ $ ~ ₺ ~ ¥ ~ ₺ ~ ₴ ~ ₩ ~ ₹ ~ €
€; ฿; $; ¥; ₺; ₹
Required options
These options will be used automatically if you select this example.
Select this option if the item
boundary is a symbol or multiple
symbols. (Enter symbols below.)
Enter item boundary symbol
or regex. For example, "," or /-{1,2}/.
Output each duplicate item
only once.
If items have a different case,
then they are consider as
different items.
Use this symbol to separate
items in the duplicate list.
Delete all leading and trailing
whitespaces from the list items.
Ignore all items that
have zero length.

Pro tips Master online list tools

You can pass input to this tool via ?input query argument and it will automatically compute output. Here's how to type it in your browser's address bar. Click to try!

https://onlinetools.com/list/find-duplicate-list-items?input=jacket%2C%20scarf%20%2C%2C%20coat%2C%20skirt%2C%20pants%2C%2C%20shirt%20%2C%20dress%2C%20hat%2C%20socks%2C%20pants%2C%20dress%2C%20shirt%2C%20%2C%20coat%2C%20suit%2C%20socks%2C%20jeans%2C%20hat%2C%20slacks%2C%20hat%2C%20jeans%2C%20jeans&string-separator=true&input-separator=%252C&output-separator=%255Cn&trim-elements=true&skip-empty=true&print-unique-duplicates=true&case-sensitive=false

All List Tools

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Quickly generate a list of arbitrary length with arbitrary items.
Quickly generate a random length list with random items.
Quickly find certain items in a list.
Quickly find how many times each item appears in the list.
Quickly replace certain items in a list with new items.
Quickly remove items from a list that match a pattern.
Quickly print all list items in reverse order.
Quickly sort list items alphabetically or numerically.
Quickly shuffle list items and make it random.
Quickly randomly pick one or more items from a list.
Quickly create a downloadable image from a list.
Quickly set a new delimiter for items in a list.
Quickly remove the symbol that separates list items.
Quickly change list item delimiters to the same symbol.
Quickly remove items from the beginning or end of a list.
Quickly join all items of a list together.
Quickly create groups of multiple list items.
Quickly extract a part of a list.
Quickly remove all empty items from a list.
Quickly remove whitespace characters around list items.
Quickly create multiple copies of a list.
Quickly rotate list items to the left or right (or up and down).
Quickly enumerate list items and add a counter to them.
Quickly add bullet markers to all items in a list.
Quickly remove all bullet markers from list items.
Quickly wrap all list items in quotes.
Quickly remove all quotation marks from around list items.
Quickly add text on the left and right sides of all list items.
Quickly remove text from the left and right sides of all list items.
Quickly prepend a prefix before each list item.
Quickly delete any prefix from the beginning of all list items.
Quickly append a suffix after each list item.
Quickly delete any suffix from the end of all list items.
Quickly add or remove list items to make it a certain length.
Quickly create multiple columns from a single list.
Quickly create a palindromic list from the given list.
Quickly add new items at the beginning or end of a list.
Quickly left-pad a list with one or more items.
Quickly right-pad a list with one or more items.
Quickly remove items that repeat in a list.
Quickly apply a filter on all list items (extract certain items).
Quickly analyze a list and print its item statistics.

Coming Soon

These list tools are on the way!
Edit a List

View and edit lists in a neat browser-based list editor.

Split a List

Split list items into chunks.

Generate the Powerlist

Create the powerlist of the given list.

Find the Car of a List

Extract the first item from a list.

Find the Cdr of a List

Extract all items except the first of a list.

Apply a Function on a List

Run a JavaScript function on every list item (map function).

Reduce a List

Run the reduce function on a list.

Find Certain List Items

Quickly find and print items that interest you in a list.

Find Repeating List Items

Quickly find and print items that repeat in a list.

Delete Unique List Items

Quickly find and remove items that are unique in a list.

Extract a Sublist from a List

Given start and stop indexes, extract a sublist from a list.

Shift List Items

Shift list items to the left or right (or up and down).

Indent List Items

Add indentation to all list items.

Skew List Items

Make a list go increasingly sideways (to the left or right).

Mirror a List

Quickly create a mirror copy of a list.

Invert a List

Invert the order of items in a list (last becomes first, etc).

Convert a List to Rows

Create multiple rows from a single list.

Convert a List to Excel

Create an Excel (XLS/XLSX) file from a list.

Convert a List to PDF

Create a PDF file from a list.

Convert a Text List to a LaTeX List

Create a LaTeX list from a regular text list.

Convert a Text List to a HTML List

Create a HTML list from a regular text list.

Convert a Text List to a Markdown List

Create a Markdown list from a regular text list.

Compare Two Lists

Find the difference between two lists.

Compare Three Lists

Find the difference between three lists.

Remove One List from Another

Remove elements from a list that appear in the other list.

Find Common Items in Lists

Find items that are shared between two or more lists.

Find Distinct Items in Lists

Find items that are unique in two or more lists.

Zip Two Lists

Join two or more lists together item by item.

Unzip Two Lists

Split an interleaved list into two or more separate lists.

Merge Two Lists

Append a second list at the end of the first list.

Pair List Items

Create pairs from all list items.

Pop List Items

Remove list items at certain index positions.

Push List Items

Add new items at the end of a list.

Splice a List

Modify a list in-place by adding, replacing, or removing items.

Flatten a List

Remove all indentation levels from a list and make it flat.

Make List Items Bold

Quickly apply the bold effect to all list items.

Make List Items Italic

Quickly apply the italic effect to all list items.

Make List Items Cursive

Quickly rewrite all list items in cursive.

Change List Item Font

Quickly change the font of all list items.

Add an Underscore to List Items

Quickly add an underscore to all list items.

Add a Strikethrough to List Items

Quickly add a strikethrough to all list items.

Make List Items Title Case

Quickly change the letter case of all items to title case.

Make List Items Proper Case

Quickly change the letter case of all items to proper case.

Make List Items Random Case

Quickly randomly change the letter case of all items.

Make List Items Lowercase

Quickly change the letter case of all items to small letters.

Make List Items Uppercase

Quickly change the letter case of all items to capital letters.

Remove List Item Counter

Quickly remove any numeration from a list of items.

Create an Empty List

Generate a list with no items (just bullet points).

Visualize a List

Quickly create a graphical representation of a list.

Create a List Cloud

Create an image with a cloud of list items.

Create a Spiral List

Create an image with list items going in a spiral.

Create a ZigZag List

Make list items go in a zigzag.

Add Errors to a List

Add errors and corruption to a list.

Base64-encode a List

Convert any list to base64 encoding.

Base64-decode a List

Convert any list from base64 encoding back to a list.

URL-encode a List

Convert any list to URL encoding.

URL-decode a List

Convert any list from URL encoding back to a list.

Convert a List to JSON

Create a JSON array from a list.

Convert JSON to a List

Create a list from a JSON array.

Convert a List to XML

Create an XML document from a list.

Convert XML to a List

Create a list from an XML document.

Convert a List to YAML

Create a YAML file from a list.

Convert YAML to a List

Create a list from a YAML file.

Convert a Text List to a Binary List

Create a binary list from a text list.

Convert a Binary List to a Text List

Create a text list from a binary list.

Compress a List

Compress a list so it uses less space.

Scroll a List

Create an animation with a list being scrolled.

Let Zalgo Destroy a List

Let Zalgo loose on a list and create list-chaos.


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