> ## Documentation Index > Fetch the complete documentation index at: https://docs.signupbreeze.com/llms.txt > Use this file to discover all available pages before exploring further. # Add a shift > Adds a shift to an existing event. Times are wall-clock (`14:30`) and are read in the event's own timezone — do not send an offset or a date. Requires the `slots:write` scope. ## OpenAPI ````yaml https://api.signupbreeze.com/openapi.yaml post /v1/events/{event_id}/slots openapi: 3.0.3 info: title: SignUpBreeze API description: >- Manage events, shifts, and signups programmatically — from your own scripts, an automation platform, or an AI agent. ## Authentication Every request needs a bearer token, which an organization owner or admin creates under **Organization settings → API**. Tokens belong to the organization rather than to the person who created one, so an admin leaving does not break a live integration. Each token carries a set of scopes, and every endpoint states the scope it requires. A request whose token lacks the scope is refused with `403`. **Every token expires**, after at most a year and by default after exactly that. An expired token is refused with `401`, the same as a revoked one, so plan to create a replacement before the expiry date shown in settings — nothing using the old token keeps working past it. ## Rate limiting Requests are throttled per API token, not per organization — issuing more tokens does not raise the ceiling. The limit varies by plan: 30 requests/min on Free and Calendar, 120 on Starter, 300 on Pro. Every response carries `X-RateLimit-Limit` and `X-RateLimit-Remaining`. Exceeding the limit returns `429`, with `Retry-After` and `X-RateLimit-Reset` added to that response so you know when to try again. ## Idempotency Writes accept an `Idempotency-Key` header. Send the same key again and the original response is replayed rather than the write happening twice — worth using anywhere a retry is possible, which is most places an agent is involved. ## Pagination Collections are cursor paginated. Follow `meta.next_cursor` rather than assuming page numbers. ## Scoping Everything a token can reach belongs to its organization. Another organization's record answers `404` rather than `403`, so a token cannot be used to discover that it exists. version: 1.0.0 servers: - url: https://api.signupbreeze.com security: - default: [] tags: - name: Events description: >- Create and manage events. Every endpoint is scoped to the organization that owns the token — another organization's event responds `404`, not `403`, so a token cannot be used to discover that it exists. - name: Organization description: |- The organization a token belongs to. - name: Shifts description: >- The time slots volunteers sign up for. Shift times are wall-clock strings like `14:30`, interpreted in the parent event's timezone against its start date — you never send a date or an offset for a shift. - name: Signups description: >- Who has signed up. Read-only in v1: signups are created through the public event page, which is deliberately the only way a volunteer is added. externalDocs: description: SignUpBreeze documentation url: https://docs.signupbreeze.com/api-reference/introduction paths: /v1/events/{event_id}/slots: parameters: - in: path name: event_id description: The ID of the event. example: 019fdf11-4bb2-7039-92c3-9e7f1ee711a1 required: true schema: type: string - in: path name: event description: The event's id. example: 019fdf11-4bb2-7039-92c3-9e7f1ee711a1 required: true schema: type: string post: tags: - Shifts summary: Add a shift description: >- Adds a shift to an existing event. Times are wall-clock (`14:30`) and are read in the event's own timezone — do not send an offset or a date. Requires the `slots:write` scope. operationId: addAShift parameters: - in: header name: Idempotency-Key description: '' example: a7f3c1e0-2b44-4f6e-9c1d-8e5b0a2d7f31 schema: type: string requestBody: required: true content: application/json: schema: type: object properties: title: type: string description: What the shift is called. example: Grill Master location: type: string description: Where this shift happens, if not the event location. example: North gate nullable: true start_time: type: string description: Wall-clock start as HH:MM. Omit for an all-day shift. example: '11:00' nullable: true end_time: type: string description: Wall-clock end as HH:MM. Must be after start_time. example: '13:00' nullable: true capacity: type: integer description: How many volunteers are needed. Your plan caps the maximum. example: 4 required: - title - capacity responses: '201': description: '' content: application/json: schema: type: object example: data: id: 019ff256-ece7-7109-b06e-fd801fcc2ba1 event_id: 019ff256-ece6-731f-a2ca-97baa9200f82 title: Setup Team location: null is_virtual: false start_time: '2026-10-28T00:14:13+00:00' end_time: '2026-10-28T02:14:13+00:00' capacity: 10 filled: 0 remaining: 10 created_at: '2026-08-11T19:40:10+00:00' updated_at: '2026-08-11T19:40:10+00:00' properties: data: type: object properties: id: type: string example: 019ff256-ece7-7109-b06e-fd801fcc2ba1 event_id: type: string example: 019ff256-ece6-731f-a2ca-97baa9200f82 title: type: string example: Setup Team location: type: string example: null nullable: true is_virtual: type: boolean example: false start_time: type: string example: '2026-10-28T00:14:13+00:00' end_time: type: string example: '2026-10-28T02:14:13+00:00' capacity: type: integer example: 10 filled: type: integer example: 0 remaining: type: integer example: 10 created_at: type: string example: '2026-08-11T19:40:10+00:00' updated_at: type: string example: '2026-08-11T19:40:10+00:00' '404': description: no such event, or it belongs to another organization content: application/json: schema: type: object example: message: Not found. properties: message: type: string example: Not found. '422': description: capacity exceeds the plan limit content: application/json: schema: type: object example: message: The capacity field must not be greater than 100. errors: capacity: - The capacity field must not be greater than 100. properties: message: type: string example: The capacity field must not be greater than 100. errors: type: object properties: capacity: type: array example: - The capacity field must not be greater than 100. items: type: string components: securitySchemes: default: type: http scheme: bearer description: >- Create a token under Organization settings → API. Tokens are shown once, on creation. They belong to the organization, not to you, so they keep working if you leave the team. API access is included on every plan; the rate limit depends on the plan. ````