Secure Password Generator

Uniform generation with guaranteed classes

The generator joins the selected lowercase, uppercase, digit, and symbol classes after exclusions. It draws every position independently from that complete effective alphabet, then accepts the whole candidate only when every selected class appears. Conditioning uniform candidates this way keeps every accepted string equally likely; the page does not use the common pick-one-per-class and shuffle shortcut.

Browser crypto.getRandomValues supplies unsigned 32-bit values. ToolNeko discards the incomplete tail of the 32-bit range before applying modulo, giving each pool index the same number of accepted source values. If secure randomness is unavailable or a fixed generation budget is exhausted, no password is shown.

Custom exclusions without silent fallback

You may exclude arbitrary characters from the 94 printable ASCII password characters, except space, with a 64-character raw limit. The optional look-alike preset excludes 0O1Il|. Duplicate exclusions count once, and excluding a character from a disabled class is recognized without changing the active alphabet.

If exclusions empty a selected class, the generator names that class and stops before requesting randomness. It does not ignore the exclusion, disable the class, or substitute another character. The receipt reports selected classes, each effective size, the total alphabet, recognized exclusions, and how many characters were actually removed from selected classes.

Exact sample space and a careful entropy claim

The exact constrained sample count uses inclusion-exclusion with integer arithmetic: it counts strings of the chosen length over the effective alphabet that contain every selected class. The displayed entropy is the conservative lower tenth of log2 of that exact count, calculated with BigInt rather than floating rounding.

This is random-choice entropy for this generator configuration. It is not a time-to-crack estimate, a claim about a human-chosen password, or a substitute for a password manager and the rules of the service where you will use the password.

No history and explicit clearing

ToolNeko keeps only the current generated value. Any length, class, preset, or custom-exclusion edit clears that value immediately. Clear now removes the page copy while preserving your settings. Optional 30-second, 60-second, or 5-minute expiry shows a countdown and clears early when the page becomes hidden.

Leaving the page clears the displayed password for every expiry setting, including Off, and returning through browser history does not restore it. Clearing releases this page's references and text; JavaScript cannot guarantee physical memory erasure or remove a password already written to the operating-system clipboard.

Random-character scope

This version creates one random-character password. It does not create passphrases, PINs, batches, pronounceable words, saved history, vault records, breach lookups, downloads, or share links. Password-manager storage and account features remain outside this page.