TOTP Generator

Generate the current RFC 6238 time-based one-time password from a base32 secret, and show how many seconds it has left.

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Input
Output
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About totp generator

TOTP Generator is one page doing one thing. No account, no settings to sync, no history building up somewhere.

No server sees this. That is a consequence of how the tool is built rather than a policy someone wrote down, which is the version worth trusting.

You will find it under Developer tools, alongside 11 other tools for the same sort of job.

Runs in this tab, so nothing you type is uploaded.

How to use it

01
Start it
Every control is on the tool itself. Keyboard shortcuts, where there are any, are listed beside it.
02
Watch it run
It updates in the page as you go. Nothing is sent anywhere, so it keeps working with the network off.
03
Close when done
Nothing is stored between visits. Reloading gives you a clean start rather than picking up where you left off.

Examples

The RFC 6238 SHA1 test secret at T=59
A fixed timestamp, since a real run would use the current time
Input
secret: GEZDGNBVGY3TQOJQGEZDGNBVGY3TQOJQ
timestampSeconds: 59
Output
Code: 287082
Seconds remaining: 1
Period start: 30
Period end: 60

Questions

Does TOTP Generator work offline?+

Yes. It is JavaScript running in this tab, so once the page has loaded it needs nothing further from the network. Put the machine in flight mode and it carries on. Nothing you do here is sent anywhere, because there is nowhere for it to go.

Does it remember anything between visits?+

No. Reload the page and it starts from nothing. There is no account, no saved state and no cookie holding your last session. That is a deliberate trade: it cannot lose your data because it never keeps any.

Is it accurate?+

Timing comes from performance.now(), the high resolution clock the browser provides, rather than from setInterval, which drifts by a few milliseconds every tick and compounds over minutes. What can still shift things is the browser throttling a tab in the background, so leave it visible if the timing matters.

Does it make a sound?+

Where a sound makes sense, it is generated with the Web Audio API rather than loaded as a file, so there is nothing to download and nothing to block. Browsers refuse to start audio until you have interacted with the page, which is why the first press is what switches it on.

Can I use TOTP Generator on a phone?+

Yes. The controls are sized for touch and the layout collapses to one column on a narrow screen. Bear in mind that a phone locking its screen will suspend the page, and timing stops with it.