Random String Generator
Generate random strings and tokens from a character set you control.
About the Random String Generator
The Random String Generator produces unpredictable strings and tokens from a character set you define. Pick the length, how many strings you want at once, and which character types to draw from — lowercase letters, uppercase letters, digits, and symbols — then add any extra characters of your own. Every string is built with your browser's built-in cryptographic random number generator (crypto.getRandomValues), the same class of randomness used for real security work, and nothing is ever transmitted or stored.
Random strings show up everywhere: API keys, session tokens, temporary passwords, invite codes, database record IDs, cache-busting suffixes, coupon codes, and test fixtures. Whatever you need one for, this tool gives you fine-grained control over the alphabet and length so the output fits your format exactly, without pulling in an external service or leaking a single character to a server.
How to use
- Set the length of each string (1–256 characters). A batch appears automatically as soon as the page loads.
- Set the count — how many strings to generate at once (1–50). Each line in the output is one independent string.
- Choose character types. Tick lowercase, uppercase, digits, and symbols in any combination. The generator draws from the union of everything you select.
- Add custom characters (optional) in the text field to extend the pool — handy for URL-safe sets like
-_.~or a fixed vocabulary. Duplicates are ignored automatically. - Click Regenerate any time for a fresh batch, then Copy all to place every string (one per line) on your clipboard.
If you turn off every character type and leave the custom field empty, the pool is empty and generation is blocked with a prompt to pick at least one set — there is nothing to draw characters from otherwise.
Frequently asked questions
Are these strings actually random and safe to use as tokens?
Yes. Every character comes from crypto.getRandomValues, the browser's cryptographically secure random generator, combined with rejection sampling so each character in your pool is equally likely — no bias toward any particular letter or symbol. This is genuinely unpredictable randomness, not the weak Math.random() used by many web toys, so the output is suitable for security-sensitive tokens and IDs.
Are my strings sent to a server or saved anywhere?
No. Generation happens entirely in your browser with JavaScript. The strings are never uploaded, logged, or stored — not even by us. Once you close or refresh the page they are gone, so copy anything you want to keep right away.
How long should a random string be?
It depends on the purpose. For a hard-to-guess token, aim for enough length and pool size that the total number of possibilities is astronomically large — a 24-character string drawn from letters and digits is already far beyond brute-force. For short human-friendly codes (invites, coupons) you can go shorter and drop symbols and look-alike characters for readability.
What does the custom characters field do?
It adds whatever you type to the character pool, on top of the sets you have checked. Use it to include punctuation a checkbox does not cover, to build a URL-safe alphabet like -_.~, or to restrict output to a specific vocabulary by unchecking every set and typing only the characters you want. Repeated characters are collapsed so no single one becomes more likely.
Can I generate many strings at once?
Yes. Set the count up to 50 and each line in the output box is a separate, independently generated string. Copy all copies the whole batch — one string per line — which pastes cleanly into a spreadsheet column, a config file, or a list of test fixtures.
Why is the Regenerate button sometimes disabled?
Because no character type is selected and the custom field is empty, leaving an empty pool. Tick at least one of lowercase, uppercase, digits, or symbols — or type some custom characters — and generation is enabled again. This guard prevents producing empty or meaningless strings.
Can I reproduce the exact same strings later?
No, and that is intentional. There is no seed or history: each batch is freshly random and never saved, because a stored or reproducible token is a token that can leak. If you need a specific string again, copy it now and store it somewhere safe like a password manager or secrets vault.