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Programmable SMS API · live on Free

SMS API that delivers in seconds, with the carrier paperwork done.

Send transactional SMS to any country in seconds. Senddio handles the carrier registration, country routing and compliance paperwork so you do not have to. The same simple /v1/send endpoint that sends your email also sends your text messages — just change the channel field to "sms".

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● Free forever · No card · All 6 channels · AI credits
POST /v1/send · channel: sms
200 OK · 38ms
curl https://api.senddio.com/v1/send \
  -H "Authorization: Bearer sdo_live_…" \
  -H "Content-Type: application/json" \
  -d '{
    "channel": "sms",
    "to":      "+14155550123",
    "body":    "Your order #A-7714 shipped — track at sndd.io/t/abc",
    "tags":    { "type": "shipping" }
  }'

# → status: queued → sent → delivered (<3s typical)
Channel
SMS
Twilio (managed for you)
Free plan
10/mo
sampler limit
Same endpoint
/v1/send
POST · Bearer auth
Latency
<50ms
queue accept · p99
How it works

SMS, made boring on purpose.

The carrier paperwork, the country routing, the "why didn't it arrive" investigations — we did all of it. Once. For you.

01
Step 01
You give us a phone number.
Any country, any carrier. We figure out which rules apply and route around the ones that block you.
02
Step 02
You write the message.
One line of body text. Same endpoint as your email. No SDK switch.
03
Step 03
It lands in seconds.
Through carrier-approved routes we maintain so you never read another rejection letter from a regulator.
04
Step 04
Their reply comes back to you.
Threaded under the original send, ready for a human or an agent to pick up where you left off.

One endpoint, one key, one bill. That is all.

The shift

Stop staring at carrier paperwork. Ship the message.

  • No more reading carrier rejection letters at 11pm.
  • No more managing a separate Twilio account.
  • No more skipping SMS tests because they cannot run in CI.
  • No more “where is my order?” landing in your support inbox.

Senddio handles the paperwork. You handle the customers.

Beyond the obvious

Whatever your team can imagine, this endpoint will send.

Real teams ship sms on Senddio for everything from order receipts to late-night customer apologies. Here are a few of the things they have built — and the kinds of things your team will dream up next month.

OTP that lands before the user looks upPassword reset for an account they forgotFraud alert before the second swipeAppointment reminder 24h, then 1h beforeShipping ETA with the driver's first nameFlight delay before the airline tells themRide-arriving ping when the car turns the cornerPrescription refill, ready for pickupHotel check-in code at 2:59pmEvent ticket QR for the doorLock combination for the cabin, expires SundayOTP that lands before the user looks upPassword reset for an account they forgotFraud alert before the second swipeAppointment reminder 24h, then 1h beforeShipping ETA with the driver's first nameFlight delay before the airline tells themRide-arriving ping when the car turns the cornerPrescription refill, ready for pickupHotel check-in code at 2:59pmEvent ticket QR for the doorLock combination for the cabin, expires Sunday
Donation thanks within thirty secondsPayroll-deposit confirmation on the 1stLow-stock alert to the buyer, not the customerOn-call escalation when Slack got ignoredCustomer win-back from a churn-risk scoreDietitian reminder to drink water at 11amAgent triage handoff to a human on SaturdayPolling-place reminder on election morningClass cancelled, refund coming, sorryLottery winner notification (we hope)AI shipping summary at end of dayDonation thanks within thirty secondsPayroll-deposit confirmation on the 1stLow-stock alert to the buyer, not the customerOn-call escalation when Slack got ignoredCustomer win-back from a churn-risk scoreDietitian reminder to drink water at 11amAgent triage handoff to a human on SaturdayPolling-place reminder on election morningClass cancelled, refund coming, sorryLottery winner notification (we hope)AI shipping summary at end of day
The thing you'll build next month
If you can describe it in one sentence, you can ship it on /v1/send.
Read the docs
What you get

Production-ready sms, on day one.

The boring infrastructure — signing, retries, suppressions, webhook verification, audit — is done. Your code is one POST.

  • Twilio-routed delivery, managed for you
  • E.164 number validation, country-code routing
  • OTP-grade latency: queued in <50ms, sent in ~1s
  • Inbound SMS replies threaded into Logs
  • Per-recipient suppression list
  • Phone-verification gate on Free plan (anti-abuse)
  • Per-country send limits & cost caps
From teams who switched

You're in good company on SMS.

Composite quotes from interviews with current Senddio customers shipping sms in production.

Login codes now arrive in under one second at the 99th percentile. Sign-up drop-off fell four points overnight. The before-and-after dashboards spoke for themselves.
Mei H.
Authentication lead · SaaS, 12 million users
Carrier registration paperwork was the single most painful thing on my desk. Senddio means I never have to look at it again. That alone is worth the price.
Devon K.
Staff engineer · marketplace
Test mode gives us predictable codes, so our SMS tests now run automatically for the first time in three years. We have caught a whole new class of regressions.
Ana P.
QA lead · healthtech
Compared to your alternatives

Senddio SMS vs. running Twilio yourself

FeatureSenddioDoing it yourself
Twilio account setup— (we own it)Yours to manage
Multi-channel SDK1 SDKTwilio + SendGrid + …
Unified billingOne invoiceOne per provider
AI agent toolsClaude MCP + OpenAIBuild yourself
Spam score before sendBuilt-inBuild yourself
Your next 30 days

What changes once you ship SMS on Senddio.

01
Day 1
First OTP delivered to a real US number
02
Day 3
International routing live across 40 countries
03
Week 1
CI green with deterministic test-mode codes
04
Day 30
99.8% delivery, zero carrier paperwork on you
●Every milestone above ships on the Free plan. No card, no upgrade gate.
RelatedA2P 10DLC— US carrier registration for business SMSOTP— One-time passwords — 2FA via SMS
FAQ

SMS — FAQ

Senddio routes SMS through Twilio, but Senddio holds the relationship and handles the regulatory work. You do not need your own Twilio account, US carrier registration paperwork, or sender-ID approvals for typical transactional sending. Senddio routes each message to the right number type per country.

Senddio accepts your send into the queue in under 50ms. Typical end-to-end delivery is under 3 seconds in the United States and 5 to 10 seconds internationally. Beyond that, carrier filtering is the largest variable nobody can fully control.

Yes. The free plan includes 10 SMS messages per month with phone verification to prevent abuse. Upgrade to Starter ($9 a month) or Pro ($79 a month) for production volumes.

Yes. Replies arrive on the same Logs feed as your outbound messages, threaded under the original send. You can forward them to Slack or Telegram for human triage, or to your own webhook for AI-agent handling.

Yes. Tag any SMS with type:otp and Senddio prioritises it on the queue, redacts the code in the Logs UI, and gives you a deterministic test-mode code generator so your continuous integration tests can verify delivery without sending real messages.

Other channels
Email
Transactional email API
WhatsApp
WhatsApp Business API
Push
Push notification API
Slack
Slack messaging API
Telegram
Telegram bot messaging

Ship sms in 5 minutes.

Free forever — on the same plan as all 5 other channels, plus AI credits.

Start free See pricing
● 300 emails/day · All 6 channels · AI credits · No card