---
title: Verify a specific slot is still available
description: "Race-condition pre-flight before creating a booking: recomputes availability for the slot's customer-local date and answers whether the exact start_time is still offered by that host."
api_method: POST
api_path: "/v1/availability/check"
canonical_url: https://wiblo.app/docs/developers/api/availability/check-slot-availability
last_updated: 2026-07-28T18:08:25+02:00
md_url: https://wiblo.app/docs/developers/api/availability/check-slot-availability.md
---

# Verify a specific slot is still available

`POST /v1/availability/check`

Race-condition pre-flight before creating a booking: recomputes availability for the slot's customer-local date and answers whether the exact `start_time` is still offered by that host. Available to any active member. Per-user rate-limited at 60/60s.

## Headers

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `X-Wiblo-Workspace` | `string` | Yes | Workspace id the call is scoped to. The actor must hold an active membership in it; a foreign or unknown id collapses onto 404 WORKSPACE_NOT_FOUND. |

## Request body

| Field | Type | Required | Description |
| --- | --- | --- | --- |
| `service_id` | `string` | Yes | Id of the service the slot belongs to. |
| `member_id` | `string` | Yes | The assigned host to verify the slot against (required, unlike the listing query). |
| `start_time` | `string` | Yes | Exact slot start to verify, as a UTC ISO 8601 datetime; availability is answered by exact match against the listed slot times. |
| `timezone` | `string` | No | IANA time zone used to resolve the slot's customer-local date for the recomputation. Defaults to `"UTC"`. |

## Request

**curl**

```bash
curl https://api.wiblo.app/v1/availability/check \
  -X POST \
  -H "Authorization: Bearer $WIBLO_TOKEN" \
  -H "X-Wiblo-Workspace: $WIBLO_WORKSPACE_ID" \
  -H "Content-Type: application/json" \
  -d '{
  "service_id": "3f8a2b9c-51d4-4e0b-9c6a-7d2e8f1a4b5c",
  "member_id": "5f2d8c1b-7e4a-4b9d-a6c3-1d8e5f2a7b4c",
  "start_time": "2026-08-24T10:00:00.000Z",
  "timezone": "Europe/London"
}'
```

**TypeScript**

```ts
import { createSdk, checkSlotAvailability } from "@workspace/sdk"

const sdk = createSdk({ baseUrl: "https://api.wiblo.app" })

const { data, error } = await checkSlotAvailability({
  client: sdk,
  headers: { "X-Wiblo-Workspace": "..." },
  body: {
    "service_id": "3f8a2b9c-51d4-4e0b-9c6a-7d2e8f1a4b5c",
    "member_id": "5f2d8c1b-7e4a-4b9d-a6c3-1d8e5f2a7b4c",
    "start_time": "2026-08-24T10:00:00.000Z",
    "timezone": "Europe/London"
  },
})
```

## Example response

```json
{
  "available": true
}
```

## Responses

**`200`** — Whether the slot is still available. Returns `CheckSlotResponse`.

| Field | Type | Required | Description |
| --- | --- | --- | --- |
| `available` | `boolean` | Yes | Whether the exact `start_time` is still offered by that host. |
| `reason` | `string` | No | Why the slot is unavailable; present only when `available` is `false`. |

**`400`** — Body failed Zod validation (`VALIDATION_FAILED`). Returns `ApiErrorEnvelope`.

**`401`** — No valid session cookie or `wbl_*` bearer was present. Returns `ApiErrorEnvelope`.

**`404`** — The workspace or service collapsed (`WORKSPACE_NOT_FOUND` / `SERVICE_NOT_FOUND`) or the member is not an assigned host (`HOST_NOT_FOUND`). Returns `ApiErrorEnvelope`.

**`422`** — The service has no assigned hosts (`SERVICE_HAS_NO_HOSTS`). Returns `ApiErrorEnvelope`.

**`429`** — Rate limit exceeded. The body's `error.code` is `RATE_LIMITED` and `error.details.retry_after` is the same number of seconds as the `Retry-After` header. Returns `ApiErrorEnvelope`.