---
title: "Busy blocks for one or more accounts"
method: POST
path: "/v1/calendar/free-busy"
tags: ["Calendar"]
---

# Busy blocks for one or more accounts

`POST /v1/calendar/free-busy`

## Request

- Base URL: `https://zernio.com/api`
- URL: `https://zernio.com/api/v1/calendar/free-busy`
- Auth: HTTP bearer

## Request body

- object
  - `accountIds` string[], required
  - `from` string, date-time, required
  - `to` string, date-time, required

## Response `200`

One entry per account, busy blocks in UTC

- object
  - `data` object[]
    - `accountId` string
    - `from` string, date-time
    - `to` string, date-time
    - `busy` BusyBlock[]
      - `start` string, date-time
      - `end` string, date-time

## Other responses

- `400`: Invalid request
- `401`: Missing or invalid API key. `code` is `missing_credentials` when no Authorization header was sent and `invalid_credentials` when the key is unknown, revoked or expired.
- `412`: The connected account cannot serve this request until something outside the request changes. Two codes: - `account_scope_missing`: the account was connected without the area this endpoint needs (`details.grantedAreas`, `details.missingArea`), or Google reports the grant lacks a permission. Reconnect with a wider `scopes=`. - `admin_consent_required` (Microsoft): the tenant requires an administrator's approval. `details.adminConsentUrl` is the Microsoft Entra admin-consent link to hand to one; it opens in a browser with no API key and stays valid for one hour. `GET /v1/connect/microsoft/admin-consent` mints a fresh one.

## Changes

- **2026-10-27** `0a24331f5431`: 1 info
  - endpoint added

[Operation history](https://skmtc.dev/zernio/apis/zernio-api/changes/v1/calendar/free-busy/post.md)

---

[API](https://skmtc.dev/zernio/apis/zernio-api.md) - [All operations](https://skmtc.dev/zernio/apis/zernio-api/llms.txt) - [OpenAPI document](https://skmtc.dev/zernio/apis/zernio-api/revisions/c319eb5d95b6?raw)