# crypto-random-string > Generate a [cryptographically strong](https://en.wikipedia.org/wiki/Strong_cryptography) random string Can be useful for creating an identifier, slug, salt, PIN code, fixture, etc. Works in Node.js and browsers. ## Install ```sh npm install crypto-random-string ``` ## Usage ```js import cryptoRandomString from 'crypto-random-string'; cryptoRandomString({length: 10}); //=> '2cf05d94db' cryptoRandomString({length: 10, type: 'base64'}); //=> 'YMiMbaQl6I' cryptoRandomString({length: 10, type: 'url-safe'}); //=> 'YN-tqc8pOw' cryptoRandomString({length: 10, type: 'numeric'}); //=> '8314659141' cryptoRandomString({length: 6, type: 'distinguishable'}); //=> 'CDEHKM' cryptoRandomString({length: 10, type: 'ascii-printable'}); //=> '`#Rt8$IK>B' cryptoRandomString({length: 10, type: 'alphanumeric'}); //=> 'DMuKL8YtE7' cryptoRandomString({length: 10, characters: 'abc'}); //=> 'abaaccabac' ``` ## API ### cryptoRandomString(options) Returns a randomized string. [Hex](https://en.wikipedia.org/wiki/Hexadecimal) by default. ### cryptoRandomStringAsync(options) Returns a promise which resolves to a randomized string. [Hex](https://en.wikipedia.org/wiki/Hexadecimal) by default. For most use-cases, there's really no good reason to use this async version. From the Node.js docs: > The `crypto.randomBytes()` method will not complete until there is sufficient entropy available. This should normally never take longer than a few milliseconds. The only time when generating the random bytes may conceivably block for a longer period of time is right after boot, when the whole system is still low on entropy. In general, anything async comes with some overhead on it's own. ```js import {cryptoRandomStringAsync} from 'crypto-random-string'; await cryptoRandomStringAsync({length: 10}); //=> '2cf05d94db' ``` #### options Type: `object` ##### length *Required*\ Type: `number` Length of the returned string. ##### type Type: `string`\ Default: `'hex'`\ Values: `'hex' | 'base64' | 'url-safe' | 'numeric' | 'distinguishable' | 'ascii-printable' | 'alphanumeric'` Use only characters from a predefined set of allowed characters. Cannot be set at the same time as the `characters` option. The `distinguishable` set contains only uppercase characters that are not easily confused: `CDEHKMPRTUWXY012458`. It can be useful if you need to print out a short string that you'd like users to read and type back in with minimal errors. For example, reading a code off of a screen that needs to be typed into a phone to connect two devices. The `ascii-printable` set contains all [printable ASCII characters](https://en.wikipedia.org/wiki/ASCII#ASCII_printable_characters): ``!"#$%&\'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~`` Useful for generating passwords where all possible ASCII characters should be used. The `alphanumeric` set contains uppercase letters, lowercase letters, and digits: `ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789`. Useful for generating [nonce](https://developer.mozilla.org/en-US/docs/Web/API/HTMLOrForeignElement/nonce) values. ##### characters Type: `string`\ Minimum length: `1`\ Maximum length: `65536` Use only characters from a custom set of allowed characters. Cannot be set at the same time as the `type` option. ## Related - [random-int](https://github.com/sindresorhus/random-int) - Generate a random integer - [random-float](https://github.com/sindresorhus/random-float) - Generate a random float - [random-item](https://github.com/sindresorhus/random-item) - Get a random item from an array - [random-boolean](https://github.com/arthurvr/random-boolean) - Get a random boolean - [random-obj-key](https://github.com/sindresorhus/random-obj-key) - Get a random key from an object - [random-obj-prop](https://github.com/sindresorhus/random-obj-prop) - Get a random property from an object - [unique-random](https://github.com/sindresorhus/unique-random) - Generate random numbers that are consecutively unique ---

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