REST API (integration)
A REST API is an interface that lets different software communicate over HTTP using standard operations on resources identified by URLs. In the messaging context, it allows sending messages, creating contacts or reading conversations from external systems such as management software, CRMs and e-commerce, without going through the graphical interface. Together with webhooks, it is the foundation of any integration between platforms.
REST organizes communication around resources, each with an address: contacts, messages, conversations. Operations use the standard HTTP methods: GET to read, POST to create, PUT or PATCH to update, DELETE to remove. Responses travel as JSON with status codes indicating the outcome. This uniformity makes REST APIs integrable from any language and readable at a glance for developers.
In the WhatsApp context, a typical REST API exposes sending messages and templates to a number, managing contacts and tags, reading conversations. Authentication happens with an API key to be guarded like a password. Before integrating, it's worth checking rate limits, the error format and the presence of complementary webhooks for inbound events, because sending alone covers only half the flow.
SendApp provides REST APIs to send WhatsApp messages and templates from your software, with API key authentication and complementary webhooks to receive events and replies.
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