toolember

Randomizer

Random Number Generator

Free online randomization tools, generate random numbers, roll dice (D4–D100), flip coins, and shuffle lists. Perfect for games, raffles, D&D sessions, and decision-making. No sign-up, runs entirely in your browser.

How to Use

Random Number

  1. Set min/max range
  2. Choose how many numbers
  3. Toggle "no duplicates" or "sorted"
  4. Click Generate and copy results

Dice Roller

  1. Select die type (D4–D100)
  2. Set number of dice (up to 20)
  3. Click Roll for instant results
  4. See total and average for multiple dice

Coin Flip

  1. Choose Single or Batch mode
  2. Single: click coin to flip with animation
  3. Batch: set count, see heads/tails tally
  4. Great for probability experiments

List Randomizer

  1. Paste list (one item per line)
  2. Click Shuffle List
  3. Items reorder randomly
  4. Copy output or shuffle again

Common Uses

Games & D&D

Roll D20 for attacks, D6 for damage, or multiple dice at once. Works for D&D, Pathfinder, and any tabletop RPG.

Raffles & Giveaways

Generate winning ticket numbers, or paste a list of names and shuffle to pick a fair winner.

Decision Making

Flip a coin for yes/no decisions, or randomize a list of options and pick from the top.

Statistics & Probability

Batch coin flip lets you run probability experiments. Generate large random datasets for testing.

Pseudorandom vs. True Random Numbers

Every result here comes from JavaScript's Math.random(), a pseudorandom number generator (PRNG). A PRNG produces numbers using a deterministic algorithm seeded from the browser's internal state, so the sequence looks statistically random but is not derived from unpredictable physical noise. This is more than sufficient for dice rolls, coin flips, raffles, and shuffling a playlist.

It is not appropriate for cryptography, security tokens, or real-money gambling, where a cryptographically secure PRNG (crypto.getRandomValues) or a hardware-based true random number generator sourced from atmospheric noise or radioactive decay (such as random.org) is required instead. The practical difference: a PRNG's output could theoretically be predicted if an attacker knew the internal seed state, which never matters for a game night but matters a great deal for generating a password or encryption key.

How the Fisher-Yates Shuffle Works

The List Randomizer uses the Fisher-Yates (Knuth) shuffle: it walks the list from the last item to the first, and at each step swaps the current item with a randomly chosen item from the remaining unshuffled portion, including itself. This runs in linear time and, critically, gives every possible ordering of the list an equal probability of occurring.

This matters because a naive approach, such as assigning each item a random number and sorting by it, is not perfectly uniform and can subtly favor certain orderings depending on the sort algorithm's stability. Fisher-Yates avoids that bias entirely, which is why it is the standard algorithm used in shuffling implementations across most programming languages.

Dice Probability and Expected Values

For a single fair die with n sides, every face has an equal 1/n chance, and the expected (average) value across many rolls is (n+1)/2. A D6 averages 3.5, a D20 averages 10.5, and a D100 averages 50.5. Rolling multiple dice at once, as the tool's dice count option allows, changes the shape of the outcome: the sum of two D6 rolls is not evenly distributed like a single die but forms a triangular distribution peaking at 7, since there are more combinations that add up to 7 (1+6, 2+5, 3+4, and their reverses) than any other total.

This is useful for tabletop game design and probability practice: rolling several dice and summing the results narrows the range of likely outcomes toward the average, which is exactly why games use multiple smaller dice (2d6, 3d6) instead of one large die when they want more predictable, bell-shaped results rather than a flat, equally-likely spread.

Frequently Asked Questions

How does the random number generator work?▾
Our tool uses JavaScript's built-in Math.random() function to generate random numbers within your specified range. You can generate multiple numbers at once, exclude duplicates, and sort the output. The numbers are generated entirely in your browser and are not sent to any server.
Is this truly random?▾
The tool uses a pseudorandom number generator (PRNG) which is sufficient for games, raffles, and casual use. For cryptographic security or lottery-grade randomness, you would need a hardware random number generator or a service like random.org.
How do I roll dice online?▾
Select the "Dice Roller" tab, choose your die type (D4, D6, D8, D10, D12, D20, or D100), and how many dice to roll. Click "Roll" to see your results. The tool shows individual rolls plus the total and average for multiple dice.
What dice types are supported?▾
We support the standard polyhedral dice used in tabletop games: D4 (4-sided), D6 (6-sided), D8 (8-sided), D10 (10-sided), D12 (12-sided), D20 (20-sided), and D100 (100-sided). You can roll up to 20 dice at once.
How do I flip a coin online?▾
Go to the "Coin Flip" tab. Use "Single Flip" for a one-time coin toss with animation, or "Batch Flip" to flip multiple coins at once and see the heads/tails tally. The batch mode is useful for probability experiments.
How does the list randomizer work?▾
Paste your list (one item per line) into the input box and click "Shuffle List". The tool uses the Fisher-Yates shuffle algorithm to randomly reorder your items. This is great for picking contest winners, randomizing playlists, or drawing names.
Can I generate random numbers without duplicates?▾
Yes. Check the "No duplicates" box in the Random Number tab. This ensures each number appears only once. Note that if you request more numbers than the range allows (e.g., 10 numbers from 1-5), the tool will stop early.
Are my results saved?▾
The last 5 results for each tab are saved in your browser's local storage for convenience. This allows you to see recent rolls or generations. Nothing is stored on our servers, everything stays on your device.
What is a D20 dice roller used for?▾
The D20 (20-sided die) is most commonly used in tabletop role-playing games like Dungeons & Dragons. It's the primary die for attack rolls, ability checks, and saving throws. Our dice roller works for D&D, Pathfinder, and other TTRPGs.
Can I use this for raffles and giveaways?▾
Yes. Use the Random Number tab to pick winners by number, or the List Randomizer to shuffle a list of names and pick from the top. For public contests, showing the screen share during the draw adds transparency.