Random String Generator
Cryptographically random strings — presets (hex, base58, base64url), license-key grouping, memorable mode, and an entropy meter.
About this ToolHow it works, benefits & use casesTap to collapse
Need a secret, an API key, a PIN, or a batch of unique IDs? The Random String Generator builds them from the browser’s Web Crypto API using rejection sampling, so every character is uniform with no modulo bias. Pick a character-set preset — alphanumeric, letters only, digits, hex (upper or lower), Bitcoin Base58, Base64URL, or symbols — or switch to a fully custom set. You can exclude similar-looking characters (i l 1 L o 0 O) and ambiguous ones ({ } [ ] ( ) and friends), set a length up to 10,000, and add license-key-style grouping with your own separator, prefix, and suffix. A live entropy meter shows the bit strength of your settings, and a memorable mode strings together NATO phonetic words instead of random characters. Generate up to 100 at once, copy individual values, or download them all. Nothing is sent anywhere — generation runs entirely on your device.
How to Use
- 1Choose a Mode: "Characters" for random character strings, or "Memorable words" for NATO-word passphrases.
- 2In Characters mode, pick a Character set preset (or "Custom…") and set the Length; in Memorable mode, set words per string, separator, and capitalization.
- 3Optionally exclude similar or ambiguous characters, and add a group size, group separator, prefix, or suffix for license-key formatting.
- 4Set "How many" (1–100) to generate a batch, and watch the entropy meter update with your bit strength.
- 5Click Regenerate to roll fresh values, then copy any single string or download all generated strings as a text file.
Key Benefits
- Uses the Web Crypto API with rejection sampling — uniform, unbiased output suitable for secrets
- Ten character-set presets including hex, Base58, and Base64URL, plus a fully custom set
- Exclude similar (i l 1 L o 0 O) and ambiguous characters to avoid transcription errors
- License-key formatting with group size, custom separator, prefix, and suffix
- Live entropy meter rates each configuration weak / fair / strong / very strong in bits
- Memorable mode produces readable NATO-word passphrases as an alternative to random characters
- Generate up to 100 strings at once and download them all in one click
Common Use Cases
- Generating API keys, session tokens, or secrets with a known entropy target
- Creating numeric PINs or hex identifiers with a fixed character set
- Producing formatted license keys like XXXX-XXXX-XXXX with grouping and a prefix
- Seeding test databases with a batch of unique random IDs
- Building easy-to-dictate passphrases for shared credentials using memorable mode
Options
i l 1 L o 0 O
{ } [ ] ( ) / \\ etc.
Generated (5)
UoYV6iDges8l6Ny3f4MTgw0BFAmVzOON4U8zQ8o2Pr1A6XxqrcpQnwHmfJPnOR3DF6JkMPDatfM2mqpf
UoYV6iDges8l6Ny3 f4MTgw0BFAmVzOON 4U8zQ8o2Pr1A6Xxq rcpQnwHmfJPnOR3D F6JkMPDatfM2mqpf
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Yes. Strings are generated with the browser’s crypto.getRandomValues and a rejection-sampling routine, which avoids the modulo bias that plain remainder math introduces for character-set sizes that don’t divide evenly into 2³². Every position in the string is drawn uniformly from the active character set.
It reports the Shannon entropy of the random portion — length multiplied by log2 of the character-set size — rounded to whole bits. It then labels the result weak (under 40 bits), fair (40–71), strong (72–127), or very strong (128+), so you can size a secret to the strength you need.