Cron Expression Parser

Parse cron expressions into human-readable descriptions with upcoming schedules

GET 1 credit /v1/cron-parse

curl "https://devtools.toolkitapi.io/v1/cron-parse?expression=*/15+*+*+*+*&count=3"

import httpx

resp = httpx.get(
    "https://devtools.toolkitapi.io/v1/cron-parse?expression=*/15+*+*+*+*&count=3",
)
print(resp.json())

const resp = await fetch("https://devtools.toolkitapi.io/v1/cron-parse?expression=*/15+*+*+*+*&count=3", {
});
const data = await resp.json();
console.log(data);

# See curl example

Response 200 OK

{
  "valid": true,
  "expression": "*/15 * * * *",
  "description": "Every 15 minutes",
  "next": [
    "2024-03-15T10:15:00+00:00",
    "2024-03-15T10:30:00+00:00",
    "2024-03-15T10:45:00+00:00"
  ],
  "timezone": "UTC"
}

Try It Live

Description

Parse cron expressions into human-readable descriptions with upcoming schedules

How to Use

1

1. Pass the cron expression in the `expression` query parameter. URL-encode spaces as `+` or `%20`.

2

2. Optionally set `count` to control how many upcoming times are returned (1–50, default 5).

3

3. Optionally set `tz` to get scheduled times in a specific timezone (default UTC).

4

4. Check the `description` field for a human-readable summary and `next` for the upcoming fire times.

About This Tool

Cron Expression Parser validates a standard 5-field cron expression, generates a human-readable description of the schedule, and lists the next N scheduled execution times.

Feed it any cron schedule — from simple intervals like `*/5 * * * *` to complex patterns like `0 9 1-15 * 1-5` — and get back a plain-English description plus a preview of upcoming fire times so you can verify the expression does what you expect.

Why Use This Tool

Schedule verification — Confirm a cron expression fires at the expected times before deploying
Documentation — Generate human-readable descriptions for cron jobs in runbooks or READMEs
Debugging — Check next execution times when a scheduled task isn't running as expected
Quick preview — Preview the next 50 runs to catch edge cases around month boundaries or weekdays

Frequently Asked Questions

Does it support 6-field (with seconds) cron?

No. Only standard 5-field cron expressions (minute, hour, day-of-month, month, day-of-week) are supported.

Can I use special characters like L, W, #?

The parser uses `croniter` which supports standard cron syntax including ranges (`1-5`), steps (`*/15`), and lists (`1,15`). Vixie cron extensions like `L`, `W`, and `#` are not supported.

What happens with an invalid expression?

The response returns `valid: false` with an `error` field explaining the issue.

Start using Cron Expression Parser now

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