Providers
What is the Sendblue iMessage API?
Sendblue is a REST API for sending and receiving real iMessages, with automatic SMS and RCS fallback. It publishes its documentation openly, offers a free sandbox, states a SOC 2 Type II posture, and prices dedicated lines at $100 per month. It is the strongest default for a team that has a developer.
What it does
- Send and receive iMessages through a documented REST endpoint.
- Automatic SMS and RCS fallback — one call, correct channel, no routing logic in your code.
- Webhooks for delivery, read and inbound reply events.
- A free sandbox, so you can send yourself a real message before paying anything.
- Public documentation detailed enough to write a client straight from the page.
What it costs
| Tier | Price | What it is |
|---|---|---|
| Free sandbox | $0 | Build against the API before paying for a line |
| AI Agent | $100 | Per month, per dedicated line |
| Enterprise | Custom | Volume and negotiated terms |
Where it is the wrong choice
- Nobody on the team writes code. The API is the product. Miss Blue sells the inbox instead.
- You send forty messages a month. A per-line plan is poor value; LoopMessage's $20 shared sender is the cheaper test.
- You want it wired into your CRM for you. Tuco AI does the implementation as part of onboarding.
Test it in an hour
The sandbox needs no card. Send one message to your own phone with curl, point the status callback at a request bin, and reply from the phone to watch the inbound webhook fire. That tells you more than any review, including ours.
The request
curl --request POST 'https://api.sendblue.co/api/send-message' \\
--header 'sb-api-key-id: YOUR_KEY_ID' \\
--header 'sb-api-secret-key: YOUR_SECRET' \\
--header 'Content-Type: application/json' \\
--data-raw '{
"number": "+19998887777",
"content": "Your 2pm window is confirmed.",
"status_callback": "https://acme.co/webhooks/imessage"
}'Sendblue's documented request shape. Check their docs for the current version before building against it.
What happens next
- Sendblue accepts the request and returns a message handle. Nothing has been delivered yet — this is the step most often mistaken for a delivery.
- It routes to a line: a real Apple account, on hardware Sendblue operates, holding the number assigned to you.
- Apple delivers it as a genuine iMessage. From the recipient's side there is nothing unusual — a blue bubble from a number.
- If the recipient is not on iMessage, Sendblue falls back to SMS or RCS automatically rather than failing.
- Events fire against your callback: delivered, read if they have receipts enabled, and any reply.
The infrastructure question
There is no wholesale access to iMessage, so Sendblue — like every provider in this category — operates Apple accounts and devices at scale. That is the architecture rather than a criticism; what separates a good operator from a bad one is monitoring, redundancy and identity hygiene. What is actually behind your number.
Ridge Auto
iMessage
POST /send-message → arrives here, blue, from your assigned number.
Reply → webhook fires against your endpoint
This page also answers
- sendblue imessage api how it works
Further reading
Go deeper
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