{
"message": "Completed successfully",
"dateList": [
"2026-08-03T09:00:00Z",
"2026-08-05T09:00:00Z",
"2026-08-07T09:00:00Z",
"2026-08-10T09:00:00Z",
"2026-08-12T09:00:00Z",
"2026-08-14T09:00:00Z"
]
}
curl --location --request POST 'https://zylalabs.com/api/13510/rrule+api/29947/expand+rrule' --header 'Authorization: Bearer YOUR_API_KEY'
--data-raw '{
"rrule": "FREQ=WEEKLY;BYDAY=MO,WE,FR",
"startTime": "2026-08-03T09:00:00Z",
"endTime": "2026-08-14T23:59:59Z"
}'
After signing up, every developer is assigned a personal API access key, a unique combination of letters and digits provided to access to our API endpoint. To authenticate with the RRULE API simply include your bearer token in the Authorization header.
| Header | Description |
|---|---|
Authorization
|
Required
Should be Bearer access_key. See "Your API Access Key" above when you are subscribed.
|
No long-term commitment. Upgrade, downgrade, or cancel anytime.
Expands an iCalendar RRULE into occurrence dates between a start and end time.
The RRULE API returns a success message along with a `dateList`, which is an array of RFC 3339 timestamps representing each occurrence of the specified recurrence rule within the given time window.
The key fields in the response data are `message`, which indicates the success of the operation, and `dateList`, which contains the array of occurrence timestamps generated from the provided RRULE.
The Expand RRULE endpoint accepts three parameters: `rrule` (the recurrence rule string), `startTime` (the start timestamp in RFC 3339 format), and `endTime` (the inclusive end timestamp in RFC 3339 format).
The response data is organized in a JSON format, containing a `message` field for status and a `dateList` field that holds an array of timestamps. Each timestamp corresponds to an occurrence of the recurrence rule within the specified time frame.
Typical use cases include calendar and scheduling applications that need to generate specific dates from a stored RRULE, as well as booking systems, reminders, and job schedulers that require expanded date patterns for a defined range.
Users can utilize the returned `dateList` to schedule events, send reminders, or populate calendars with specific occurrence dates. Each timestamp can be directly integrated into scheduling systems or applications that require precise date information.
If the provided RRULE or timestamps are invalid, the API will return an HTTP 400 error, indicating a bad request. Users should ensure that their inputs conform to the expected formats to avoid this error.
Users can customize their data requests by modifying the `rrule`, `startTime`, and `endTime` parameters. By changing these values, users can generate occurrence dates for different recurrence patterns and time frames as needed.
To obtain your API key, first sign in to your account and navigate to the API you want to use. From the API's Pricing section, choose a plan and complete the subscription process. Once subscribed, return to the API page and you will see your API Access Key displayed at the top of the documentation page. You can use this key to authenticate your requests.
You can’t switch APIs during the free trial. If you subscribe to a different API, your trial will end and the new subscription will start as a paid plan.
The free trial lasts for 7 days and allows you to make up to 50 API requests.
No, the free trial is available only once, so we recommend using it on the API that interests you the most. Most of our APIs offer a free trial, but some may not include this option.
Yes. If the API offers a free trial, you will see a "Free 7-Day Trial" option in its Pricing section. The trial lasts for 7 days and allows up to 50 API requests, enabling you to evaluate the API before subscribing to a paid plan.
Zyla API Hub is like a big store for APIs, where you can find thousands of them all in one place. We also offer dedicated support and real-time monitoring of all APIs. Once you sign up, you can pick and choose which APIs you want to use. Just remember, each API needs its own subscription. But if you subscribe to multiple ones, you'll use the same key for all of them, making things easier for you.
You can monitor your API usage through the response headers included with every request:
x-zyla-api-calls-monthly-used: Shows the total number of API requests you have used during the current billing period.
x-zyla-api-calls-monthly-remaining: Shows the number of API requests you have remaining for the current billing period.
Yes, you can cancel your subscription at any time. Simply go to the Pricing section of the API you're subscribed to and click the "Unsubscribe" button.
Please note that upgrades, downgrades, and cancellations take effect immediately. Once your subscription is canceled, access to the service will end immediately, regardless of any remaining API calls in your quota.
Please have a look at our Refund Policy: https://zylalabs.com/terms#refund