Random String Generator
Generate random strings from a secure source: pick length, count and character sets, exclude look-alikes and keep results unique. Shows the entropy in bits.
Random strings are handy for API keys, test data, tokens, coupon codes and DNA-style sequences. This generator draws every character from the browser’s cryptographically secure random source with rejection sampling, so there is no bias toward any character. Pick the length, character sets and rules, and it reports the entropy in bits.
How to use this tool
- Set the length and how many strings you need.
- Choose character sets, or type a custom alphabet.
- Optionally exclude look-alike characters, require each set and keep results unique.
- Generate and copy the strings.
Formula
Entropy per string = length × log₂(pool size). A 16-character string from a 62-character pool has 16 × log₂(62) ≈ 95.3 bits.
Rejection sampling discards raw random bytes that would fall outside a whole number of pool-sized ranges, which removes the "modulo bias" that a plain remainder would introduce.
Example
Sixteen characters from the 62-letter upper+lower+digit pool give about 95.27 bits of entropy — far beyond anything guessable by brute force.
Frequently asked questions
Are these really random?
They use crypto.getRandomValues, the same cryptographically secure generator browsers use for security operations — not the predictable Math.random.
What does "exclude look-alikes" do?
It removes I, l, 1, O and 0, which are easy to confuse when a code is read aloud or typed from print. It slightly lowers the pool size and entropy.
Why require one of each set?
Some systems demand at least one uppercase, lowercase and digit. The option guarantees that while still shuffling the characters so the required ones are not predictable.
Last updated:
Page address with these inputs: https://kakao.mobile/tools/random-string-generator/
Cite or embed this tool
kakaoCalc. (2026, November 8). Random String Generator. https://kakao.mobile/tools/random-string-generator/
“Random String Generator.” kakaoCalc, 8 Nov. 2026, kakao.mobile/tools/random-string-generator/.
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