Sendblue

A REST API for sending and receiving real iMessages, with SMS and RCS fallback.

Overview

Sendblue's pitch is that you should not have to think about the delivery path. You send one request with a phone number and a body, and it arrives as an iMessage if the recipient has one and as RCS or SMS if they do not. For a small business that is the important part — your customer list is not sorted by handset, and you should not have to sort it.

The feature surface goes past plain text. Sendblue's site lists read receipts, typing indicators, high-quality media, voice memos, video, photos, contact cards (vCards), and FaceTime Audio calls originating from the same number you message from. There are webhooks for delivery receipts and inbound replies, which is what you need if you want a reply to trigger anything in your own system.

It also markets itself hard at teams building AI agents over messaging — the example on their homepage is an assistant that books flights and runs errands over iMessage. If your plan is 'a bot answers the first message and a human takes over', that is the shape they are designing for.

One practical note they call out: no A2P 10DLC registration. Traditional SMS providers in the US make you register a brand and campaign before you can send, which routinely takes days or weeks. Skipping that is a real time saving, but it is not a compliance exemption — consent and opt-out obligations still apply to you.

What stands out

What Sendblue does well

Blue bubble first, fallback automatic

Sends as iMessage where available and re-routes to RCS or SMS where it is not, without you branching on the recipient.

Native iMessage signals

Read receipts, typing indicators and expressive send styles are exposed as API parameters rather than being lost in translation.

Beyond text

Voice memos, video, photos, vCards and FaceTime Audio from the same line the messages come from.

Webhooks for everything inbound

Delivery receipts and replies are pushed to your endpoint, so a customer answer can trigger work in your CRM.

No A2P 10DLC registration

Skips the carrier brand-and-campaign registration that gates US SMS senders. Consent rules still apply to you.

Compliance posture at the top tier

SOC 2 and HIPAA are listed under their enterprise plan — relevant if you are in healthcare or handling regulated data.

Pick Sendblue if

Developers who want a documented REST API and SDKs rather than a UI
Teams layering an AI agent on top of a real phone line
Anyone who needs graceful fallback to SMS and RCS for non-Apple contacts
Businesses that want to skip A2P 10DLC registration to launch faster

Look elsewhere if

Someone who only wants a shared inbox and will never touch an API
Very high volume outbound at low per-line cost — dedicated lines are priced per line

The API

Send a message

Note the link in the message body — it carries UTM parameters, so when the customer taps it the visit is attributed to this exact campaign instead of vanishing into direct traffic.

From public docs

How the tagging works

bash

curl --request POST 'https://api.sendblue.co/api/send-message' \
  --header 'sb-api-key-id: YOUR_SB_API_KEY_ID' \
  --header 'sb-api-secret-key: YOUR_SB_API_SECRET_KEY' \
  --header 'Content-Type: application/json' \
  --data-raw '{
    "number": "+19998887777",
    "content": "Your 2pm window is confirmed. Details: https://acme.co/visit?utm_source=imessage&utm_medium=messaging&utm_campaign=appointment-confirm",
    "status_callback": "https://acme.co/webhooks/sendblue"
  }'

Request shape from Sendblue's public API documentation. Check their docs for the current version before you build against it.

Pricing

What Sendblue costs

Tiers as listed on sendblue.com. Third-party comparison sites quote materially different figures for Sendblue, so treat their own pricing page as the only authority and confirm before you budget.

Free sandbox

Build against the API before you pay for a line.

Shared phone numbers
Up to 10 verified contacts
Full API access for testing

AI Agent

$100/month per dedicated line

A production line for an agent or a small outbound motion.

Dedicated phone line
1,000 inbound contacts per day
Webhooks and SDKs

Enterprise

Custom

Multiple lines, outbound teams, and compliance requirements.

Multiple dedicated lines
SOC 2 and HIPAA
Volume pricing

Check current pricing

Last checked August 2026.

Feature checklist

Capabilities

Outbound iMessage
Two-way replies
SMS / RCS fallback
Group chats
Typing indicators
Read receipts
Reactions / tapbacks
Rich media
Webhooks
Shared team inbox(limited)
Dedicated number
Free sandbox

Before you commit

Do this first

The sandbox is free on every provider in this category. There is no reason to sign a contract before you have sent yourself a message.

Create the free sandbox account and send a message to your own phone.
Check what share of your customer list is actually on iPhone — your CRM may already know.
Write the three messages you would send most often, and read them out loud.
Tag the links in them before the first send, not after.
Run one play on a slice of your list and compare it to what you send today.

Independent guide, commercial links

We are not affiliated with Sendblue. Links to providers on this site carry tracking parameters that identify us as the referrer. Everything above comes from Sendblue’s own public pages, and vendor marketing figures are labelled as such rather than presented as findings.

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