> ## Documentation Index > Fetch the complete documentation index at: https://docs.dialbird.io/llms.txt > Use this file to discover all available pages before exploring further. # Create a webhook subscription > Subscribes a `target_url` to a single event type (REST Hooks model — one subscription per event type per URL). The response includes the plaintext `signing_secret` **once** — store it now; it is never returned again. Use it to verify the `X-Dialbird-Signature` on every delivery. ## OpenAPI ````yaml /openapi.yaml post /subscriptions openapi: 3.1.0 info: title: Dialbird Public API version: 1.0.0 description: > The Dialbird Public API is a versioned, machine-to-machine REST surface for building automations on top of Dialbird (Zapier, n8n, Make, custom scripts). ## Authentication All endpoints except `GET /health` require an OAuth 2.0 bearer access token obtained via the Authorization Code flow against Dialbird's OIDC provider. The token is a signed JWT with `aud: "public-api"`; the API verifies it against the issuer's JWKS. Send it on every request: ``` Authorization: Bearer ``` Access tokens must **never** be passed as a `?access_token=` query parameter — requests that do are rejected with `401 invalid_token`. ## Request & response conventions - All request and response bodies are JSON (`application/json`). - Field names are `snake_case`. - Every response carries an `X-Request-Id` header. Include it when contacting support. Clients may supply their own via the `X-Request-Id` request header (`^[A-Za-z0-9_-]{1,64}$`); otherwise the API generates one. - Phone numbers are always E.164 (e.g. `+15551234567`). ## Idempotency Write endpoints (`POST /contacts`, `POST /messages`) accept an optional `Idempotency-Key` header (≤255 chars). Retrying a request with the same key and identical body replays the original response without re-running the operation. Reusing a key with a *different* body returns `409 idempotency_key_reused`; a retry while the first request is still in flight returns `409` with code `idempotency_in_progress`. Keys are retained for 24h. ## Rate limiting Authenticated requests are limited per `(business, oauth_client)`; anonymous requests (only `GET /health`) are limited per IP. Every response includes: - `X-RateLimit-Limit` — requests allowed in the current window - `X-RateLimit-Remaining` — requests left in the window - `X-RateLimit-Reset` — unix epoch seconds when the window resets A `429 rate_limited` response additionally carries a `Retry-After` header (seconds). ## Errors Errors share one envelope: ```json { "error": { "code": "not_found", "message": "…", "field": "to", "request_id": "req_…" } } ``` `field` is present only for validation errors that map to a specific input. contact: name: Dialbird Support email: team@usechalkboard.com servers: - url: '{origin}/api/v1' description: Dialbird Public API base URL variables: origin: default: https://app-staging.dialbird.io description: The Dialbird deployment origin (matches the OIDC issuer host). security: - OAuth2: [] tags: - name: System description: Unauthenticated health checks. - name: Identity description: The authenticated principal. - name: Contacts description: Create and update contacts. - name: Messages description: Send SMS messages. - name: Webhooks description: Manage REST-Hook webhook subscriptions. paths: /subscriptions: post: tags: - Webhooks summary: Create a webhook subscription description: | Subscribes a `target_url` to a single event type (REST Hooks model — one subscription per event type per URL). The response includes the plaintext `signing_secret` **once** — store it now; it is never returned again. Use it to verify the `X-Dialbird-Signature` on every delivery. operationId: createSubscription requestBody: required: true content: application/json: schema: type: object required: - event_type - target_url properties: event_type: $ref: '#/components/schemas/EventType' target_url: type: string format: uri description: HTTPS URL that receives event deliveries. example: https://hooks.zapier.com/hooks/standard/123/abc/ responses: '201': description: Subscription created. headers: X-Request-Id: $ref: '#/components/headers/RequestId' content: application/json: schema: type: object properties: id: type: string event_type: $ref: '#/components/schemas/EventType' target_url: type: string format: uri signing_secret: type: string description: Returned only at creation. Prefixed `whsec_`. example: whsec_8f3c… status: $ref: '#/components/schemas/SubscriptionStatus' created_at: type: string format: date-time '400': $ref: '#/components/responses/ValidationError' '401': $ref: '#/components/responses/Unauthorized' '403': $ref: '#/components/responses/Forbidden' '429': $ref: '#/components/responses/RateLimited' security: - OAuth2: - api:webhooks components: schemas: EventType: type: string enum: - message.incoming.received - message.outgoing.delivered - call.incoming.completed - call.outgoing.completed SubscriptionStatus: type: string enum: - active - failing - disabled description: | `failing` after consecutive delivery failures cross the warning threshold; `disabled` after they cross the hard limit or the receiver returns `410 Gone`. Error: type: object required: - error properties: error: type: object required: - code - message - request_id properties: code: $ref: '#/components/schemas/ErrorCode' message: type: string field: type: string description: >- Present only for validation errors tied to a specific input field. request_id: type: string ErrorCode: type: string enum: - validation_error - invalid_phone_number - invalid_event_type - missing_token - invalid_token - expired_token - insufficient_scope - forbidden - business_suspended - not_found - conflict - idempotency_key_reused - idempotency_in_progress - gone - unprocessable_entity - rate_limited - internal_error headers: RequestId: description: Echoes the request id (client-supplied or generated). schema: type: string WWWAuthenticate: description: Bearer challenge. schema: type: string RetryAfter: description: Seconds to wait before retrying. schema: type: integer RateLimitLimit: description: Requests allowed in the current window. schema: type: integer RateLimitRemaining: description: Requests remaining in the current window. schema: type: integer RateLimitReset: description: Unix epoch seconds when the window resets. schema: type: integer responses: ValidationError: description: The request body failed validation. content: application/json: schema: $ref: '#/components/schemas/Error' Unauthorized: description: Missing, malformed, invalid, or expired token. headers: WWW-Authenticate: $ref: '#/components/headers/WWWAuthenticate' X-Request-Id: $ref: '#/components/headers/RequestId' content: application/json: schema: $ref: '#/components/schemas/Error' Forbidden: description: >- Token lacks the required scope, or the business is suspended / not associated. content: application/json: schema: $ref: '#/components/schemas/Error' RateLimited: description: Rate limit exceeded. headers: Retry-After: $ref: '#/components/headers/RetryAfter' X-RateLimit-Limit: $ref: '#/components/headers/RateLimitLimit' X-RateLimit-Remaining: $ref: '#/components/headers/RateLimitRemaining' X-RateLimit-Reset: $ref: '#/components/headers/RateLimitReset' content: application/json: schema: $ref: '#/components/schemas/Error' securitySchemes: OAuth2: type: oauth2 description: | Authorization Code flow against Dialbird's OIDC provider. The issued access token is a JWT with `aud: "public-api"`, verified against the issuer JWKS. flows: authorizationCode: authorizationUrl: https://app-staging.dialbird.io/oidc/auth tokenUrl: https://app-staging.dialbird.io/oidc/token refreshUrl: https://app-staging.dialbird.io/oidc/token scopes: api:me: Read the authenticated business, user, and granted scopes. api:contacts:read: Read contacts. api:contacts:write: Create and update contacts. api:messages:read: Read messages. api:messages:write: Send messages. api:calls:read: Read calls. api:webhooks: Manage webhook subscriptions. ````