Utilities
Four small tools for everyday developer work: convert Unix timestamps to dates and back, read a cron expression in plain English with its next runs, test regular expressions as you type, and generate or inspect UUIDs.
Unix timestamp converter
Paste a timestamp in seconds, milliseconds, microseconds or nanoseconds, or a date in almost any form, and see it in UTC, in your own time zone or any other, as ISO 8601 and as an HTTP date.
Cron expression explainer
Paste a schedule from a crontab, a CI pipeline or a Kubernetes CronJob to read it in words, field by field, with the next ten times it runs.
Regex tester
Type a pattern and some text: matches are marked as you type, with their numbered and named groups, and a replacement shows the result. Each test runs in the background and stops after a second, so a runaway pattern can't freeze the page.
UUID generator
Version 4 (random) or version 7 (starting with the time, so they sort by creation), one or a thousand at a time, in upper case or without dashes. Also known as GUIDs. The UUID page also reads one back: its version, and when it was made.
Questions
Is anything sent to a server?
No. All four run in your browser, and nothing you type is saved or sent.
Which time zone do they use?
Yours, as your browser reports it, next to UTC: the timestamp converter shows both and any other zone you pick, and the cron explainer lists the next runs in your time or in UTC.
Which regular expressions does the tester use?
JavaScript's own, as in browsers and Node.js, with the g, i, m, s and u flags. Other languages share the basics but differ at the edges.
Should I use UUID version 4 or 7?
Version 7 for database keys, as they sort by when they were made; version 4 when an id must not reveal when it was made.