How strong is the default 16-character password?
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With all four character sets enabled the alphabet has 90 characters, so each character contributes log₂(90) ≈ 6.49 bits and 16 characters give about 104 bits of entropy — far beyond what offline guessing attacks can search.
Is length or complexity more important?
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Length. NIST SP 800-63B recommends supporting long passwords rather than enforcing composition rules like "one symbol and one digit", because entropy grows with every added character. Four extra lowercase-only characters add more entropy than swapping a letter for a symbol.
What does the exclude look-alikes option cost?
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It removes 0, O, 1, l, I and | from the alphabet, shrinking it from 90 to 84 characters. At 16 characters that drops the entropy from about 104 to about 102 bits — a negligible price for a password a human has to read or retype.
What is modulo bias and why does rejection sampling matter?
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Mapping a random 32-bit number onto a 90-character alphabet with a plain modulo makes the first characters of the alphabet very slightly more likely, because 2³² is not a multiple of 90. Rejection sampling throws away draws from the incomplete final cycle, so the distribution is exactly uniform.
Are generated passwords stored or sent anywhere?
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No. Passwords exist only in this tab's memory until you regenerate or close it. There is no history, no analytics on the values, and no network request involved in generating or copying them.
Why is there no strength meter?
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Colored strength bars guess at human password patterns; for randomly generated passwords the entropy number is the honest measure. Anything above roughly 80 bits is beyond realistic offline attack, and the readout updates live as you change length or character sets.