API Reference

The full, field-by-field reference for the WhatsApp API is generated from the server’s own code, so it always matches what the API accepts and returns.

OpenAPI document

The OpenAPI document is public and needs no login or API key:

Format	URL
JSON	https://waba-api.startmessaging.com/api/v1/openapi.json
YAML	https://waba-api.startmessaging.com/api/v1/openapi.yaml
Swagger UI (browse and try requests)	https://waba-api.startmessaging.com/api/v1/docs

Import the JSON or YAML into Postman, Insomnia or any OpenAPI tool, or generate a typed client from it with a generator of your choice.

curl -o startmessaging-openapi.json https://waba-api.startmessaging.com/api/v1/openapi.json

What the document includes:

• Every endpoint under /api/v1, its request body, query parameters and response schema, with examples.
• The error codes each operation can return.
• Named request examples for POST /messages: template, authentication (OTP), text, document and interactive. Carousel cards (template.carouselCards) and limited-time offers (template.offerExpiresAt) are described on the template schema and in Send Messages.
• The scope each operation needs, as the extension field x-scope on the operation. GET /me and GET /phone-numbers need no scope.

Operations are grouped by tag: Account, Messages, Contacts, Tags, Pipeline, Templates, Conversations, Campaigns, Conversions and Webhooks. There are 10 scopes in all (see Authentication).

In the dashboard

The Developers section of the app has the same reference and tools for debugging:

• Developers → API reference: the reference built from the OpenAPI document, with code samples ready to copy.
• Developers → Logs: each API call with its result and any error. The last 500 requests from the past 7 days are kept. Requests made with an unknown key are not listed, because they belong to no workspace.
• Developers → API keys and Developers → Webhooks: manage keys, scopes and webhook endpoints.
• The API tab of the in-app help panel on every page shows the endpoints that automate that page.
• Each template’s Send via API panel shows the exact request for that template.

Base URL

https://waba-api.startmessaging.com/api/v1

All requests use HTTPS and the Authorization: Bearer sm_live_… header (see Authentication).

Endpoints at a glance

Method and path	Scope
GET /me	none
GET /phone-numbers	none
POST /messages	messages:send
GET /messages/{id}	messages:read
GET /contacts, GET /contacts/{idOrPhone}	contacts:read
POST /contacts, PATCH /contacts/{idOrPhone}, DELETE /contacts/{idOrPhone}	contacts:write
GET /tags, GET /pipeline-stages	contacts:read
GET /templates, GET /templates/{id}	templates:read
GET /conversations, GET /conversations/{id}, GET /conversations/{id}/messages	conversations:read
PATCH /conversations/{id}	conversations:write (plan with the team inbox)
GET /campaigns, GET /campaigns/{id}	campaigns:read
POST /conversions	conversions:write (Business plan: sales pipeline)
GET /webhooks, POST /webhooks, DELETE /webhooks/{id}	webhooks:manage
POST /trigger/send	messages:send (deprecated)

Versioning

/api/v1 is the customer contract. Within v1 we only add: new optional request fields, new response fields, new endpoints and new webhook event types. Removing or renaming anything would be a new version (v2).

To stay compatible:

• Ignore response fields and webhook event types you don’t recognise.
• Branch on error.code. For a code you don’t recognise, decide by HTTP status: a 429 (after Retry-After) or a 5xx is worth retrying; any other 4xx will fail the same way until the request, plan or account changes.

Deprecated: POST /trigger/send

POST /api/v1/trigger/send was the original template-sending endpoint. It still works, uses the same send path and hourly budget, and accepts clientReference, but its response keeps the old shape. Use POST /api/v1/messages for new integrations; it covers templates and every other message type.

FAQ

Do I need an API key to read the OpenAPI document? No. The JSON, YAML and Swagger UI are public. Calling the endpoints themselves needs a key.

Is there an official SDK? No. The API is plain REST with JSON, so any HTTP client works. You can generate a client from the OpenAPI document if you want typed models.

How do I see why a request failed? Check the response’s error.code and meta.requestId, then find the request in Developers → Logs, which keeps the last 500 requests from the past 7 days.

Will v1 change under me? Only by addition. Fields and endpoints are never removed or renamed within v1, so an integration that ignores unknown fields keeps working.