# Denisas Bykovas – Cal.com booking page

> I architect systems that cannot fail.**
The systems Lithuanians use to file taxes (EDS4 - VMI), move money (CENTROlink - Bank of Lithuania), and run regulated production lines - systems that make the morning news if they stop. Twenty-five years on .NET. PhD in Information Technology. .NET Foundation contributor since 2020.

The work is what nobody else wants to own - legacy stitched to regulation stitched to a release calendar that can't slip. I draw the architecture and stay close enough to the running system that the decisions still hold up after the deploy.

If the system has to keep running, we should talk.**
Three ways to engage. All start with the same question: what has to keep running, and what breaks if it does not?

Booking page: https://cal.com/denisas-bykovas

## Event types

- [30 min meeting](https://cal.com/denisas-bykovas/30min): 30 min, confirmed instantly, event type id 5542106. Details: https://cal.com/denisas-bykovas/30min.md
- [15 min meeting](https://cal.com/denisas-bykovas/15min): 15 min, confirmed instantly, event type id 5542105. Details: https://cal.com/denisas-bykovas/15min.md
- [Secret meeting](https://cal.com/denisas-bykovas/secret): 15 min, confirmed instantly, event type id 5542104. Details: https://cal.com/denisas-bykovas/secret.md

## Check availability

```http
GET https://api.cal.com/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.com/v2/bookings` request (`cal-api-version: 2026-02-25`).

## More

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