First request in a minute
curlcurl api.chronoskin.example/v4/slots \ -H "Authorization: Bearer ck_test_..." \ -d calendar="studio" \ -d day="2025-03-14"Follow the quickstart
Version 4.2 adds recurring holds
Put time on your side of the API
chronoskin turns calendars, time zones and opening hours into one bookable schedule. Start with a guide, or go straight to the endpoint you need.
API reference
42 endpoints, each with a request you can copy.
Open the referenceLibraries
Typed clients for four languages.
TSPyGoRb
Guides to start with
All 28Status
The last 30 days, measured at the edge?Timed from six regions every minute, not from inside our own network.
Slots API 99.98%
Webhooks 99.2%
- Endpoints42Across six resources
- Median response38 ms4 ms faster than in 4.1
- Requests a minute600On a live key; 60 on a test key
- Guides283 being rewritten for 4.2
Ask the people who wrote it
The forum is answered by the same six people who maintain the API, usually within a working day.
IKTMLORS+2
Open the forum
Change notes
Choose what reaches your inbox.
- Breaking changes
- New endpoints
- Monthly digest
Start with a test key
Free, rate limited, and it cannot touch a real calendar.
Guides
Twenty-eight worked examples, each one task from the first request to the last check.
-
Hold a slot, then confirm itUpdated for 4.2
Reserve a time for ten minutes while your customer pays, and confirm or release it afterwards.
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Opening hours across time zonesCalendars
Describe a week once and let the API answer in the zone of whoever is asking.
-
Receive and verify webhooksWebhooks
Check the signature, answer within five seconds and handle a delivery that arrives twice.
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Page through a long calendarGetting started
Cursors, page sizes and why the last page can be empty.
Two ways through
If you take bookings
Quickstart, holding a slot, payments in between, then webhooks.
If you show availability
Quickstart, opening hours, time zones, then caching the answers.
Hold a slot, then confirm it
A hold reserves a time for a short while without booking it. Use one whenever something has to happen between choosing a time and committing to it, such as a payment.
Create the hold
Send the calendar and the instant you want to POST /v4/holds. The answer carries an id and the moment the hold runs out, ten minutes later unless you ask for less.
const hold = await chronoskin.holds.create({ calendar: "studio", start: "2025-03-14T09:30:00Z", minutes: 45, });
What can go wrong
- The time was taken a moment ago: the answer is
409with the next free slot. - The calendar is closed that day: the answer is
422. - A test key can hold at most five slots at once.
Confirm or release
When the payment succeeds, confirm the hold and it becomes a booking. If it fails, release it at once so the time is free again; do not wait for it to run out. The holds reference lists every field.
A hold is not a booking
It is not sent to the customer's calendar and no webhook fires until you confirm it.
Do not extend a hold in a loop
A hold can be extended once. A second attempt answers 409 and the slot is released.
Keep reading
Questions about holds
How long can a hold last?
Between one and thirty minutes. Ten is the default, and one extension of the same length is allowed.
Does a hold count against my rate limit?
Creating one is a request like any other. Holding it costs nothing.
Can two holds overlap?
Only when the calendar allows more than one booking at a time, such as a class with twelve places.
Holds Stable
Reserve a time for a few minutes before it becomes a booking. Six endpoints, all under /v4/holds.
| Endpoint | What it does | State | A minute |
|---|---|---|---|
| POST/holds | Create a hold | Stable | 600 |
| GET/holds/:id | Read one hold | Stable | 1,200 |
| POST/holds/:id/confirm | Turn it into a booking | Stable | 600 |
| POST/holds/:id/extend | Add time, once | Beta | 120 |
| DELETE/holds/:id | Release it | Stable | 600 |
| PUT/holds/:id | Replace a hold | Leaves in 5.0 | 60 |
Parameters of a new hold
POST/holdscalendar, required
The calendar's short name or id. The key must have the bookings scope for it.
start, required
An instant in UTC. A local time without a zone is refused.
minutes
Length of the slot. Defaults to the calendar's own slot length.
expires_in
How long the hold lasts, in minutes, from 1 to 30.
Answer
201{
"id": "hold_8fq2",
"calendar": "studio",
"minutes": 45,
"expires_at": "09:40:00Z"
}
API keys
A key is shown once, when it is made. Keep it out of the browser and out of your repository.
New key
Requests signed with the key named Old checkout will fail at once. This cannot be undone.
Your keys
Last used?Rounded to the hour, in your own time zone.| Name | Kind | Last used | Requests today |
|---|---|---|---|
| Booking page | Live | Today, 14:00 | 8,412 |
| Back office | Live | Today, 13:00 | 1,096 |
| Old checkout | Live, unused | 41 days ago | 0 |
| Laptop | Test | Yesterday, 18:00 | 37 |