Countdown to a Unix Timestamp
How long until a given epoch value — or how long since it passed. Useful for token expiry, cache TTLs and scheduled jobs.
Time remaining
—
| Total seconds | — |
|---|---|
| Total minutes | — |
| Total hours | — |
| Total days | — |
| Target (UTC) | — |
| Target (local) | — |
Where these deadlines come from
| Field | Where you see it | Unit |
|---|---|---|
exp | JWT expiry claim (RFC 7519) | Seconds |
iat | JWT issued-at claim | Seconds |
Expires | HTTP cache header (as a date, not epoch) | — |
notAfter | TLS certificate validity end | Date |
ttl | DynamoDB item expiry | Seconds |
X-Amz-Expires | S3 pre-signed URL lifetime | Seconds (duration) |
Watch the last row: some fields are an absolute instant and some are a duration from issue. Feeding a duration into a countdown gives a date in 1970, which is usually the first sign you have mixed the two up.
Clock skew
This countdown compares the target against your own device clock. If your
machine is a few minutes off, a token that looks valid here may already be
rejected by the server. That is exactly why specifications such as JWT
recommend allowing a small leeway — typically 30 to 60 seconds — when
validating exp and nbf. If a token is failing right
at its boundary, suspect skew before suspecting the token.
Related tools
Frequently asked questions
What is this countdown for?
Enter any Unix timestamp and it shows the time remaining until that instant, updating every second. It is mainly useful for checking token expiry, cache TTLs, scheduled jobs and certificate deadlines without doing arithmetic in your head.
What if the timestamp is in the past?
It counts up instead, showing how long ago the instant was. An expired JWT, for example, will show the elapsed time since it stopped being valid.
How do I check when a JWT expires?
Decode the token and read the exp claim, which is a Unix timestamp in seconds. Paste that value here to see exactly how long is left. Note that iat (issued at) and nbf (not before) are the same format.
Can I share a countdown?
Yes — the URL updates as you type, so /countdown?t=2147483647 loads a countdown to that exact timestamp. Copy the address bar to share it.