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SendiMessage
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AvailableDirect HTTP API

Send messages from Go with the SendiMessage API

Go has an official SendiMessage module: go get github.com/sendimessage/sendimessage-go. It uses only the standard library, takes a context on every call, and returns errors instead of ignoring them, in idiomatic Go style.

Drop the client into an HTTP handler, a worker consuming a queue, or a scheduled job — anywhere your Go service decides a customer should hear something.

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What this integration enables

Transactional notifications
Order confirmations, payment receipts, and status changes triggered by your backend.
Appointment reminders
Scheduled jobs that message customers before a booking.
Operational alerts
Delivery windows, service updates, and internal notifications.
Two-way conversations
Incoming replies arrive on your webhook endpoint for routing to support or sales.

Architecture

How it fits together: Your application event, then Go server code, then SendiMessage API, then Managed messaging line, then Webhook events.
  1. Your application eventAn order ships, a booking nears, a ticket updates
  2. Go server codeBuilds the request with credentials from the environment
  3. SendiMessage APIPOST /send-message returns the queued message
  4. Managed messaging lineSMS, or iMessage on supported lines and destinations
  5. Webhook eventsDelivery status and incoming replies post back to your endpoint

Example request

Go
// go get github.com/sendimessage/sendimessage-go
package main


import (
	"context"
	"fmt"
	"log"
	"os"


	sendimessage "github.com/sendimessage/sendimessage-go"
)


func main() {
	client := sendimessage.New(
		os.Getenv("SENDIMESSAGE_KEY"),
		os.Getenv("SENDIMESSAGE_SECRET"),
	)


	msg, err := client.SendMessage(context.Background(), sendimessage.SendMessageParams{
		Number:  "+15555550123",
		Content: "Hello from SendiMessage",
	})
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(msg.MessageHandle, msg.Status) // 4e828182-… QUEUED
}

Delivery events and incoming replies

Delivery status and incoming replies arrive as signed webhook events. Verify the signature, then correlate events with your own records via the message_handle returned when you sent.

webhook event
// "outbound" event → your go endpoint
// Verify the SendiMessage-Signature header (t={timestamp},v1=HMAC-SHA256 of
// "{timestamp}.{raw body}", keyed with your webhook secret), then use
// GET /v2/messages/{message_handle} for authoritative state and match it to
// your contact_id in go.

Limitations and honest notes

  • iMessage delivery is available on supported messaging lines and destinations. Recipients without iMessage receive SMS when fallback is configured — never assume universal iMessage availability.
  • Messages are accepted asynchronously — the API returns status QUEUED and final status arrives via webhook or the message endpoints.
  • Official SDKs are published for JavaScript/TypeScript (npm: sendimessage), Python (PyPI: sendimessage), PHP (Composer: sendimessage/sdk), and Go (github.com/sendimessage/sendimessage-go). Every SDK is dependency-free and covers the full public API surface.

Security considerations

  • Load the API key pair from the environment — never commit it or embed it in client-side code.
  • Verify webhook signatures before processing events.
  • Log message handles, not message bodies, in shared logs.

Frequently asked questions

Is there an official Go SDK for SendiMessage?
Yes — install it with `go get github.com/sendimessage/sendimessage-go`. The SDK is dependency-free, covers the full public API (messages, media, lookup, contacts, lines, conversations, webhooks), and ships a webhook signature verification helper.
What does the API return when I send a message?
The API accepts messages asynchronously and responds with status "QUEUED" plus a message_handle and the line_handle it will send from. Track final delivery via GET /status, the message history endpoints, or webhook events.
Can I send iMessage from Go?
SendiMessage delivers over iMessage where the destination supports it on your managed line, and falls back to SMS when fallback is configured. iMessage is never guaranteed for every recipient.

Ready to connect Go?

Request a messaging line and a SendiMessage integration specialist will review your Go workflow and guide the setup.