# Niklas Sievers – Cal.com booking page

> Book a meeting with Niklas Sievers on Cal.com.

Booking page: https://charly.cal.eu/niklas.sievers

## Event types

- [20 Minuten mit Niklas](https://charly.cal.eu/niklas.sievers/20-minuten-mit-niklas): 30 min, confirmed instantly, event type id 346894. Details: https://charly.cal.eu/niklas.sievers/20-minuten-mit-niklas.md
- [30 Minuten mit Dr. Niklas Sievers](https://charly.cal.eu/niklas.sievers/30-minuten-mit-niklas-sievers): 30 min, confirmed instantly, event type id 332082. Details: https://charly.cal.eu/niklas.sievers/30-minuten-mit-niklas-sievers.md
- [30 Minuten mit Niklas](https://charly.cal.eu/niklas.sievers/30-minuten-mit-niklas): 30 min, confirmed instantly, event type id 309686. Details: https://charly.cal.eu/niklas.sievers/30-minuten-mit-niklas.md
- [Auftakt mit Charly](https://charly.cal.eu/niklas.sievers/auftakt-mit-charly-kopie): 30 min, confirmed instantly, event type id 306702. Details: https://charly.cal.eu/niklas.sievers/auftakt-mit-charly-kopie.md
- [Auftakt mit Charly](https://charly.cal.eu/niklas.sievers/auftakt-mit-charly): 45 min, confirmed instantly, event type id 304288. Details: https://charly.cal.eu/niklas.sievers/auftakt-mit-charly.md
- [Kennenlernen mit Dr. Niklas Sievers, Charly CEO](https://charly.cal.eu/niklas.sievers/30min): 30 min, confirmed instantly, event type id 211786. Details: https://charly.cal.eu/niklas.sievers/30min.md

## Check availability

```http
GET https://api.cal.eu/v2/slots?eventTypeId=<event type id>&start=YYYY-MM-DD&end=YYYY-MM-DD&timeZone=<IANA time zone>
cal-api-version: 2024-09-04
```

The response is `{"data":{"YYYY-MM-DD":[{"start":"<ISO 8601 with offset>"}]}}`; no API key is needed.

## Book

Each event type's `.md` document lists its required booking fields and the `POST https://api.cal.eu/v2/bookings` request (`cal-api-version: 2026-02-25`).

## More

- API docs: https://cal.eu/docs/api-reference/v2/introduction