List Randomizer

How to use the list randomizer

Type or paste your items into the List box, one item per line, and press Randomize List. The Shuffled list row shows every item once in its new order, and the copy button next to it places the whole shuffled list on your clipboard.

Items can be anything that fits on a line: names, email addresses, ID numbers, song titles, countries, tasks or whole sentences. Spaces around an item are trimmed and empty lines are skipped. You need at least two items for a shuffle to mean anything.

The shuffle happens in your browser. Pressing the button also puts your input into the page address so that the link can be shared, and opening that link starts a new shuffle, so a link never reproduces an earlier order. Avoid sharing the link if the list is private.

List size and duplicate removal

The randomizer accepts up to 100,000 items. Very long lines make that ceiling lower in practice, because the page and your browser have to hold the whole text. If a huge list is slow, replace long entries with short numbers, shuffle the numbers and look the entries up afterwards.

Tick Remove duplicates from list to keep only the first appearance of each line before shuffling. Matching is exact apart from surrounding spaces, so Apple and apple count as two different items. Removing duplicates can leave fewer than two items, in which case there is nothing to shuffle and the tool says so.

How the shuffle works

The tool uses the Fisher-Yates shuffle in the form published by Richard Durstenfeld. Working from the end of the list towards the start, it picks a random position from the part that is not yet fixed (including the current position) and swaps the two items. After the last step the order is final.

Example with four items, A B C D: step 1 picks a position among all four, say position 2 (B), and swaps it with D to give A D C B. Step 2 picks among the first three, say position 1 (A), and swaps it with C to give C D A B. Step 3 picks between the first two; choosing D leaves C D A B in place. The finished order is C D A B.

The three steps had 4, 3 and 2 choices, so there are 4 × 3 × 2 = 24 equally likely paths, and each of the 24 possible orders of four items is produced by exactly one of them. That is the property that makes the method unbiased.

number of possible orders = n! = n × (n − 1) × … × 2 × 1

The random positions come from the browser's cryptographic generator, and values that would favour some positions through rounding are discarded. A popular shortcut, sorting the list with a random comparison function, does not give every order the same probability, which is why it is not used here.

What people use a list randomizer for

Splitting into two groups. Shuffle the names and give the first half to team 1 and the second half to team 2. For more than two teams, or an uneven headcount, the random team generator does the dealing for you.

Awards and prizes. If only the top 3 or top 10 of a list should receive something, shuffle the entrants and take the first lines. Everyone has the same chance of being near the top. To draw winners directly, use the random name picker.

Chores, rotas and speaking order. List the people or tasks, shuffle, and work down the result. A teacher can use it to decide in which order students present, and a family can use it to assign this week's jobs.

Playlists and quizzes. Songs, films, flash cards or questions can be shuffled into an order nobody could predict. For rolling dice or picking from options instead of reordering, see the random dice roller and the random choice generator.

Randomizer or randomiser?

Both spellings mean the same thing. American English writes randomizer and randomize, while British English usually prefers randomiser and randomise. The tool behaves identically whichever word you searched for.