Random Letter Generator
TextEverything runs locally in your browser — nothing is uploaded
Pick a character set and a count to get a random string, plus an entropy estimate (characters × log2(alphabet size)). Every character is drawn by rejection sampling — a byte holds 256 values and 256 is not a multiple of 26, so a plain modulo would over-weight the letters A–F. Rejection sampling discards the uneven range and redraws, so all characters are equally likely. Add a separator every N characters for readability or invite codes. Set a seed to reproduce the same string — that path is pseudo-random, fine for demos and tests but not for passwords. Leave the seed blank to draw from the browser’s cryptographic source. Everything runs in your browser; nothing is uploaded.
Features
- Seven sets: uppercase, lowercase, mixed, alphanumeric, hex, no look-alikes, custom
- Generate 1 to 1000 characters
- Optional separator every N characters (space or hyphen)
- Rejection sampling keeps every character equally likely
- An entropy estimate so the strength is visible
- A seed reproduces the exact same string (not cryptographic, and the UI says so)
- Blank seed uses the browser’s cryptographic random source
How to use
- Choose a character set (enter characters for Custom)
- Set the count, and a group length and separator if you want them
- Enter a seed to reproduce a string, or leave it blank for true randomness
- The string and entropy estimate appear immediately
FAQ
- Why is rejection sampling better than a modulo?
- A byte holds 256 values and 256 is not a multiple of 26, so a modulo gives the first six letters roughly twice the chance. Rejection sampling throws away the uneven range and redraws, so every character has the same probability.
- Does a seed make it a password?
- The opposite. A seed makes it reproducible, but from a 32-bit generator, so anyone who knows the seed can recompute the string. That suits demos and tests. For a password, leave the seed blank.
- What does the entropy estimate mean?
- It is characters × log2(alphabet size), in bits — a measure of how hard it is to brute-force. A larger set and more characters raise it.
- Is anything uploaded?
- No. It is all computed in memory in your browser, no request is made, and it works offline.
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