無料オンライン乱数ジェネレーター
ワンクリックで任意の範囲の乱数を生成します。
A random number generator picks numbers with no predictable pattern — every number in the range has an equal chance of being selected. This tool uses your browser's built-in cryptographic random function for true statistical randomness, suitable for games, raffles, classroom activities, and decision-making.
Common uses for random numbers
- Raffles and giveaways: number each entry and generate a random winner
- Games and dice: simulate dice rolls or generate random outcomes
- Statistics and sampling: pick random items from a list for unbiased selection
- Decision-making: choose between options by assigning each a number
- Random PINs and codes: generate a number within a specific range
Is this truly random?
This tool uses crypto.getRandomValues() — the same API used by password managers and cryptographic applications. It produces statistically unbiased numbers, unlike Math.random() which uses a predictable pseudorandom algorithm.
Frequently Asked Questions
Are the random numbers truly random?
The tool uses the Web Crypto API (window.crypto.getRandomValues) for cryptographically secure random number generation, making it suitable for lotteries, security keys, and statistical sampling — not just pseudorandom output.
Can I generate random numbers without duplicates for a lottery?
Yes. Enable "No duplicates" and set your range. For a 6/49 lottery, set min=1, max=49, count=6, no duplicates. Each draw gives unique numbers within the range.
Can I generate random decimal numbers?
Yes. Toggle to decimal mode and specify the number of decimal places. The tool generates floating-point numbers uniformly distributed between your min and max values.
What is the maximum range and count I can use?
The tool supports ranges up to JavaScript's safe integer limit (±9 quadrillion). Count can be up to 10,000 numbers per generation. For larger datasets, export as CSV.
Can I use this to generate a random password?
For a numeric PIN, yes. For a full alphanumeric password with symbols, use the dedicated Password Generator tool which offers more character set options.
Is the 乱数ジェネレーター free to use?
Yes, the 乱数ジェネレーター on Allio Tools is completely free with no sign-up or registration required. It works directly in your browser.
How does the 乱数ジェネレーター work?
ワンクリックで任意の範囲の乱数を生成します。 No data is sent to a server — everything runs locally in your browser for maximum privacy and speed.
Do I need to install anything to use the 乱数ジェネレーター?
No installation needed. The 乱数ジェネレーター runs entirely in your web browser on any device — desktop, tablet, or mobile.
Is my data safe when using the 乱数ジェネレーター?
Completely safe. The 乱数ジェネレーター processes everything locally in your browser. No input data, results, or usage information is ever transmitted to or stored on any server.
Does the 乱数ジェネレーター work offline?
After the page loads for the first time, the 乱数ジェネレーター works without an internet connection for all client-side processing. Tools that fetch live external data (such as DNS or network lookups) require an active connection.
Are the results from the 乱数ジェネレーター truly random?
Yes. The 乱数ジェネレーター uses your browser's built-in cryptographically seeded random number generator, which provides high-quality unpredictable randomness suitable for games and fair decisions.
Can I customise what the 乱数ジェネレーター generates?
Yes. Where customisation options are available, you can add your own items, set numeric ranges, or adjust parameters before generating. Default settings are designed for the most common use case so you can get an instant result without any configuration.
Does the 乱数ジェネレーター work on all browsers?
Yes. The 乱数ジェネレーター is built with standard browser APIs and works on all modern browsers including Chrome, Firefox, Safari, and Edge — on both desktop and mobile. No plugins, extensions, or third-party software are required.
How do I save or export my results from the 乱数ジェネレーター?
Select and copy the result text to paste into any document or app. For image tools, a Download button saves the file directly to your device. Your browser's built-in screenshot function also captures results quickly. No account or login is required.