> ## Documentation Index > Fetch the complete documentation index at: https://docs.brelio.com/llms.txt > Use this file to discover all available pages before exploring further. # Free slots > Finds free slots to book a patient with a professional for a service: up to 50 start times, with the same rules as Brelio's agenda. **When to use it:** Before creating an appointment, to offer times that can be booked without a conflict. Windows up to 31 days. ## OpenAPI ````yaml /api-reference/openapi.en.json get /availability openapi: 3.1.0 info: title: Brelio API version: '1' description: >- Everything a person can do in Brelio, a program can do, with the same permissions, audit and limits. Every endpoint is derived from the operation catalogue. servers: - url: https://api.brelio.app/v1 security: [] paths: /availability: get: tags: - scheduling summary: Free slots description: >- Finds free slots to book a patient with a professional for a service: up to 50 start times, with the same rules as Brelio's agenda. **When to use it:** Before creating an appointment, to offer times that can be booked without a conflict. Windows up to 31 days. operationId: availability.search parameters: - name: professionalId in: query required: true schema: type: string format: uuid pattern: >- ^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$ description: The professional to book. - name: patientId in: query required: false schema: type: string format: uuid pattern: >- ^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$ description: >- The patient to book, when known; it does not change the slots, which are the professional’s time. - name: serviceId in: query required: true schema: type: string format: uuid pattern: >- ^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$ description: The service to book; its duration is the default length. - name: centerId in: query required: false schema: type: string format: uuid pattern: >- ^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$ description: Required when the organization has more than one center. - name: from in: query required: true schema: type: string format: date-time pattern: >- ^(?:(?:\d\d[2468][048]|\d\d[13579][26]|\d\d0[48]|[02468][048]00|[13579][26]00)-02-29|\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\d|30)|(?:02)-(?:0[1-9]|1\d|2[0-8])))T(?:(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d(?:\.\d+)?)?(?:Z|([+-](?:[01]\d|2[0-3]):[0-5]\d)))$ description: Start of the window, ISO 8601. - name: to in: query required: true schema: type: string format: date-time pattern: >- ^(?:(?:\d\d[2468][048]|\d\d[13579][26]|\d\d0[48]|[02468][048]00|[13579][26]00)-02-29|\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\d|30)|(?:02)-(?:0[1-9]|1\d|2[0-8])))T(?:(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d(?:\.\d+)?)?(?:Z|([+-](?:[01]\d|2[0-3]):[0-5]\d)))$ description: End of the window, ISO 8601. At most 31 days after `from`. - name: durationMinutes in: query required: false schema: type: integer minimum: 5 maximum: 480 description: Length of the appointment. Defaults to the service’s duration. responses: '200': description: Success content: application/json: schema: type: object properties: data: maxItems: 50 type: array items: type: object properties: startAt: type: string format: date-time pattern: >- ^(?:(?:\d\d[2468][048]|\d\d[13579][26]|\d\d0[48]|[02468][048]00|[13579][26]00)-02-29|\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\d|30)|(?:02)-(?:0[1-9]|1\d|2[0-8])))T(?:(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d(?:\.\d+)?)?(?:Z))$ description: ISO 8601, UTC. endAt: type: string format: date-time pattern: >- ^(?:(?:\d\d[2468][048]|\d\d[13579][26]|\d\d0[48]|[02468][048]00|[13579][26]00)-02-29|\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\d|30)|(?:02)-(?:0[1-9]|1\d|2[0-8])))T(?:(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d(?:\.\d+)?)?(?:Z))$ description: ISO 8601, UTC. required: - startAt - endAt additionalProperties: false durationMinutes: type: integer minimum: -9007199254740991 maximum: 9007199254740991 centerId: type: string format: uuid pattern: >- ^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$ required: - data - durationMinutes - centerId additionalProperties: false '401': description: Problem Details (RFC 9457) with a stable `code` content: application/problem+json: schema: $ref: '#/components/schemas/Problem' '402': description: Problem Details (RFC 9457) with a stable `code` content: application/problem+json: schema: $ref: '#/components/schemas/Problem' '403': description: Problem Details (RFC 9457) with a stable `code` content: application/problem+json: schema: $ref: '#/components/schemas/Problem' '422': description: Problem Details (RFC 9457) with a stable `code` content: application/problem+json: schema: $ref: '#/components/schemas/Problem' '429': description: Problem Details (RFC 9457) with a stable `code` content: application/problem+json: schema: $ref: '#/components/schemas/Problem' '503': description: Problem Details (RFC 9457) with a stable `code` content: application/problem+json: schema: $ref: '#/components/schemas/Problem' security: - bearer: [] components: schemas: Problem: type: object required: - type - title - status - code - detail - request_id - params properties: type: type: string title: type: string status: type: integer code: type: string detail: type: string request_id: type: string hint: type: string retryAfterSeconds: type: integer params: type: object securitySchemes: bearer: type: http scheme: bearer description: Brelio API key (organization or user) or a WorkOS access token. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.