Read a crontab line

Paste a cron expression (30 2 * * 1-5) or a whole crontab line: the tool says when it runs, lists the next runs, points out the traps and gives the systemd timer equivalent.

Expression or crontab line

Transparency

The line is analysed in your browser, by the scripts listed below. It never leaves this page.

Enforced by your browser
This page's Content Security Policy allows a single destination, the site's audience measurement (connect-src https://stats.r-no.fr, see below), and forbids any form submission (form-action 'none'), so even a bug could not send what you type anywhere. You can read the policy at the top of the page source.
Audience measurement
Like every page of the site, this one counts its visit with Umami, installed on R-no’s own server (stats.r-no.fr). It receives the address of the page, without parameters or anchor, the site you came from (its domain only), your browser, system, language and screen size, and the country, region and city deduced from your IP address, which is not kept. It never receives what you type, nor the result of the tool. No cookie, nothing stored in your browser; if your browser asks not to be tracked (Do Not Track), nothing is measured. The data is erased after 25 months.
  • /commun/mesure.js: the filter applied before each sending, written for R-no Toolbox. 1.4 kB
    SHA-256 225eec74fd12623d82fc05ee7d222be629ce454d081c129e8d1e249ed37ee716
  • https://stats.r-no.fr/m.js: Umami’s tracker, open source (MIT), served by the measurement server. Its fingerprint is not shown here: it changes with each version of Umami, and you cannot check from your browser that it is the published code. For that part, you have to trust R-no.
What is stored
No cookie, and nothing in the address. What you type is never stored: it disappears when you reload or close the page. Your language is given by the address itself (/en/ or /fr/): nothing is stored to remember it. Like any website, the server records the download of the page and its files in its access logs (IP address, date and time, address requested, browser name). It never receives what you type.
Code that runs here
  • app.js: the reading of the expression, the sentence, the next runs and the systemd equivalent, written for R-no Toolbox. Not minified, no third-party library. 22.6 kB
    SHA-256 f365b48ee30b79efd509b305ca5759809811d1fb20e7abce3b7e76cbb9ff1c2b
  • textes.js: the French messages of the tool, shown by its script (the rest of the French page is written into its HTML when the site is built). It only defines texts, with no logic. 9.6 kB
    SHA-256 9a8584699cf9abe5c8143da54f7485840eb7f5396b7644298fbf9aeb91a4036b
  • /commun/langue.js: the language helper, the same on every page of the site. It reads the language of the page and gives the tool its messages in that language. It stores nothing. 1.6 kB
    SHA-256 80f76f69773ef628d36d09bf8387cfedebda4529210d7120649b6f5603310631
Before you paste
This page only reads and writes text: it runs nothing and schedules nothing. A job only exists once added to a crontab (crontab -e) on the machine.
Which cron
The rules are those of Vixie cron and its descendants (cronie, Debian’s cron, macOS), including the “or” between day of month and day of week, which only applies when neither field starts with *. The next runs of 18 expressions were checked against croniter, and the systemd lines against systemd-analyze calendar.
Check it yourself
Download a script and compare its fingerprint with the one above:
curl -s https://r-no.fr/linux/cron/app.js | shasum -a 256
Limits
Extensions of other tools are refused: seconds, years, L, W, #, ? (Quartz, AWS, Kubernetes with a year…), as well as 5/15 without a range. The next runs are computed in your browser’s time zone; around a daylight saving change, cron has its own rules and may differ by one run. Searched over ten years at most.