DEVELOPER / THE EVERYDAY TOOLKIT
Timestamp Converter.
Convert Unix seconds, milliseconds and ISO dates to UTC. This is a free utility from my portfolio toolkit, with local browser processing and no account required.
Output is always UTC. ISO input must include Z or a timezone offset to avoid ambiguous local dates. Leap seconds are not modeled by JavaScript Date.
SIMPLE BY DESIGN
How to use Timestamp Converter
- Select Unix seconds, Unix milliseconds or an ISO date-time with an explicit timezone.
- Enter the value and generate the conversion.
- Compare the UTC result with the source system before using it in a query or report.
Compare times without a hidden local timezone.
APIs and logs can represent the same instant as Unix seconds, Unix milliseconds or an ISO date-time. Choose the input unit explicitly to avoid a date near 1970 caused by a seconds-versus-milliseconds mismatch. The result includes a UTC ISO value and both Unix representations. ISO input must carry Z or an offset; the converter does not assume that an unqualified local time refers to your intended timezone.
A FEW THINGS TO KNOW
A little more clarity.
Does the result use my computer’s timezone?
No. The display uses UTC. JavaScript Date has millisecond precision and does not represent leap seconds.
Is my input sent to a server?
No. This utility processes your input in your browser. URLs you paste are treated as data; the tool does not fetch them. Be careful with clipboard history on shared devices.
FROM THE JOURNAL
Format Dates Without Accidentally Changing the Day
Distinguish calendar dates from instants and make locale and time-zone decisions explicit.