OTP generator

Calculate a one-time-password test vector from a Base32 secret and counter or timestamp.

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Privacy details

OTP generator processes your input in this browser. Inputs and results are excluded from analytics. Recent tools save tool names, visit counts and last-visit times. Saved tools store only their names. Draft saving is optional and stays on this device; delete saved text with the draft controls. Loading text from a URL is optional and contacts that server; its URL and your IP address are visible to the server. An optional “Use in” action keeps a handoff in this tab. The next tool removes it on arrival and ignores it if more than a minute has passed.

Copy link includes the inputs you choose to share in the address. Anyone with that link can reopen them. Files and generated results are excluded. Password and key tools share settings only.

Base32 secret (example key shown)

More options

Mode

HOTP counter

TOTP Unix timestamp (seconds)

Digits

Your result

Reset reloads the tool with its starting values and releases open files and device controls. Saved drafts stay on this device until you delete them.

Links include your inputs and settings. Anyone with the link can see them, so leave out private text. Files and generated results are left out; random draws run again.

Keyboard shortcuts

Updated 2026-09-19

Using OTP generator

OTP generator decodes the Base32 key, signs the eight-byte moving counter with HMAC-SHA-1 and applies dynamic truncation. It preserves leading zeroes and checks the counter range.

Next: HMAC generator

A worked example

The public RFC example secret with HOTP counter 0 produces 755224. In TOTP mode at Unix timestamp 59 with eight digits, it produces 94287082.

Before you use the result

This is a protocol calculator, not an authenticator account store. The displayed example secret is public. TOTP uses the timestamp you enter, a 30-second step and SHA-1; it does not refresh as time passes.

Cite this page

Citation style

ToolOctopus. “OTP generator.” Updated 2026-09-19. https://tooloctopus.com/otp-generator.

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