One API. Every channel your customers actually read.

Why one API beats three integrations

Most teams end up with a billing pile-up nobody saw coming. SendGrid for transactional email. Mailchimp for marketing. Twilio for SMS. A separate WhatsApp Business Solution Provider for templated messages. Four invoices, four sets of credentials, four event-webhook formats your data pipeline has to normalize, four support contacts when something breaks.

Each individual product is decent. Stitched together they create the kind of overhead that only shows up at the 50-person company stage when someone in finance asks why messaging costs $14k a month and engineering can\'t produce a unified usage breakdown without three CSV exports.

A communications API is the obvious answer to that mess. The interesting question is what unification actually means at the infrastructure layer. The big CPaaS platforms describe themselves as unified but operate the channels as independent silos under one brand. That\'s what happens when you acquire your email product (SendGrid into Twilio) instead of building it. The accounts, billing, and dashboards are merged. The send infrastructure isn\'t.

We took the opposite approach. The channels share one event stream, one reputation engine, and one identity model. Below is what that practically means.

How we compare to the big CPaaS players

Where the channels are operationally unified versus where they\'re separate products under one brand

Sourced from each provider\'s public product documentation as of 2026-05. We\'ll keep this table honest. If something here is wrong, email us and we\'ll correct it.

How a unified reputation engine works in practice

Here\'s the thing nobody on the marketing pages of CPaaS sites really explains: when your email reputation goes bad with a particular customer, that customer\'s relationship with your brand is bad. They\'re not going to suddenly love your SMS. They\'re going to mark it as spam too, or block your sender ID, or just ignore it.

We use this fact. Our Cortex engine tracks engagement signal at the contact level, not just the channel level. If a recipient marks three emails as spam, we drop their SMS priority too. If they hard-bounce on email but click your WhatsApp template, we know to keep WhatsApp as the active channel and not waste send capacity retrying email.

This matters in two concrete ways. First, it stops you from making the bad-engagement signal worse by stacking another channel on top. Second, it gives the customer a coherent experience. They\'re not getting messages from "[email protected]" while simultaneously getting SMS from a number they don\'t recognize, both about the same flow.

The Cortex also runs reputation calculations at three other levels above the contact: per sender ID per channel, per domain or short-code, and per client. When the per-client temperature dips below a threshold, we apply graduated throttle controls across all of that client\'s sending. Email, SMS, and WhatsApp all slow down together so that none of them dig the reputation hole deeper while the others recover.

There\'s a deliberate trade-off here. If you genuinely want one channel to keep firing while another is on fire (you\'re running a security alert flow and the email reputation just tanked), you can override the cross-channel coupling per activity. The default is unified, the override is opt-in. That\'s how we\'ve found teams actually want to work once they\'ve thought it through.

Send your first message in three lines per channel

Same auth, same response envelope, same webhook shape. Pick the channel.

curl -X POST https://api.sendmsg.io/v1/email/send \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "to": "[email protected]",
    "from": "[email protected]",
    "subject": "Your order is on its way",
    "html": "<p>Tracking number: <strong>1Z999AA10123456784</strong></p>",
    "priority": "high"
  }'

Full API reference, response shapes, and event-webhook schema in the API Documentation. SDKs for Node.js, Python, and Go are coming Q3 2026.

Three real flows you can build on this

Pulled from actual customer integrations. The pattern that\'s shared across all three is the cross-channel coupling. Same engagement signal feeds every decision.

These three flows have one thing in common: the channel decision happens at send time, not at code-write time. That\'s the real win of a unified API. You write the intent (notify this customer, send this confirmation, reply to this ticket) and the system picks the channel based on what it knows about each recipient. Same code, better delivery.

Want only one channel?

The unified API is the recommended path. If you only need one channel today, each one is also available standalone.

Common questions