One API. Every channel.
Delivered.
send0 is the messaging infrastructure for modern engineering teams. Email, WhatsApp, and SMS through a single API — with AI-powered routing, deliverability guardrails, and compliance baked in.
npm install send0Trusted by engineers at
What we do
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Messaging infrastructure
you can ship today.
One SDK. Three channels. Zero vendor lock-in. send0 replaces the patchwork of Twilio, SendGrid, WhatsApp BSP, and 10DLC registrars with a single, typed API designed for engineers who'd rather ship features than babysit provider dashboards.
Deliverability that
scales with you.
From your first 1,000 transactional emails to 10M/day across three continents — send0 handles warmup, suppression, compliance, and carrier negotiations so your team can focus on product-market fit, not postmaster tickets.
The messaging stack
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TypeScript, Python, Go, REST. Idempotent, typed, and fast.
A single unified endpoint across channels. `POST /messages` handles email, SMS, and WhatsApp with the same payload shape. Official SDKs are fully typed, tree-shakeable, and publish JSR + npm + PyPI on every release.
Under the hood
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Routing decision · live
We pick the channel. You ship the feature.
Every message runs through a reasoning pipeline that scores channels against engagement history, cost ceilings, and send-time windows. The one that wins delivers — the rest stay on standby.
Event stream · 30s window
Every delivery, observable in real time.
Opens, clicks, bounces, read receipts, STOP keywords — all surfaced as signed webhook events. Or subscribe via server-sent events straight from the dashboard.
Benchmarks
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Faster. Cheaper. More deliverable.
Measured, not claimed.
We benchmark weekly against Resend, SendGrid, and Twilio using a 3M-message test corpus across 14 geographies. Here's how we stack up.
| Feature | send0 | Resend | SendGrid | Twilio |
|---|---|---|---|---|
| Unified API across email, WhatsApp, SMS | ||||
| AI channel routing & fallback | ||||
| Automated IP warmup & suppression | partial | |||
| Idempotency keys on every endpoint | partial | |||
| Typed SDKs (TS, Python, Go) | partial | |||
| 10DLC + WhatsApp BSP, handled for you | partial | |||
| Unified deliverability dashboard | ||||
| HMAC-signed webhooks + SSE | partial | |||
| Per-message cost ≤ industry avg |
*Comparisons based on public documentation and test-corpus measurements as of Q1 2026. Full methodology available on request.
Developer experience
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Feels like the API you
wish you had written yourself.
Typed SDKs, idempotent requests, sensible defaults. One primitive (`messages.send`) handles every channel.
import { Send0 } from "send0";
const client = new Send0({ apiKey: process.env.SEND0_KEY });
const message = await client.messages.send({
channel: "auto", // send0 picks the best channel
to: { email: "jane@acme.com", phone: "+14155550123" },
template: "order_ready",
data: { order_id: "#4821", customer: "Jane" },
idempotency_key: "order_4821",
});
console.log(message.id, message.channel);
// → msg_9f2a1c whatsappPlays nicely with
your stack.
Drop-in support for every modern framework. Edge-ready, serverless-ready, and fully tree-shakeable.
Built for every send
From first OTP to millionth campaign,
send0 runs it all.
Order confirmations, receipts, shipping updates
Deliver the moment it matters. Idempotent sends, sub-second queue times, and failover across channels ensure every message lands on the first try.
Passwordless logins, 2FA, magic links
Multi-channel OTP with automatic fallback — start on WhatsApp, fall back to SMS, fail over to email. Smart rate limits, carrier-aware routing, global delivery.
Two-way WhatsApp, support triage, broadcasts
Build conversational experiences without plumbing a BSP. Template approvals, session management, and inbound webhooks — all first-class primitives.
Drip campaigns, re-engagement, announcements
Compliance-first marketing with unsubscribe handling, reputation monitoring, and engagement-aware routing. Outperform Mailchimp on deliverability — at a fraction of the cost.
Enterprise
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For teams that can't afford to drop a message
Production-grade messaging
for production-grade teams.
From Series A startups to regulated fintechs, teams pick send0 when downtime costs real money and every delivery needs a paper trail. Single sign-on, custom SLAs, dedicated infrastructure, and the compliance surface area to pass any vendor review.
SOC 2 Type II
Independently audited controls across availability, confidentiality, and security. Report available under NDA.
GDPR · HIPAA-ready
EU and US data residency, DPA on request, BAAs available on Scale and Enterprise plans.
Encryption everywhere
TLS 1.3 in transit, AES-256 at rest. Customer-managed keys (CMEK) for Enterprise workloads.
Regional isolation
Deploy in us-east, us-west, eu-central, or ap-south. Data never leaves your chosen region.
Custom plan? Dedicated infrastructure?
Talk to our team about SLAs, regional isolation, and white-glove onboarding.
Testimonials
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What developers are saying
Loved by engineers.
Replaces three vendors. Feels like one.
migrated our OTP flow from Twilio to @send0 in an afternoon. one SDK, automatic fallback, 38% lower cost. thought this was going to be a week.
built our entire abandoned-cart flow on send0. email → 24h → whatsapp → 48h → SMS. zero carrier plumbing. recovery revenue up 11% MoM.
our inbox placement went from 87% → 99.2% the week we moved to send0. didn't change templates, didn't warm new IPs. they just handled it.
compliance review at our fintech just passed with send0 as the sole messaging vendor. SOC 2 report, DPA, HIPAA BAA, all available same-day. unheard of.
the AI router is unreasonably good. recipients who never opened our emails got re-engaged on whatsapp. +22% open rate on lifecycle, week 1.
10DLC registration via send0 took 19 hours. it took 11 DAYS last time with Twilio. still not over it.
I've been waiting for someone to build "stripe for messaging" for 4 years. @send0 actually did it. single POST /messages, every channel, every region.
idempotency keys on every POST. i didn't know how much i needed this until i had it. no more dedup logic in our queue consumer. beautiful.
send0's docs are what resend's docs used to be. clear primitives, real curl examples, no marketing fluff. shipped a whole notification system today.
the typescript SDK is what Stripe's SDK would be if it shipped in 2026. inferred types everywhere, autocomplete on the template payloads, zero surprises.
webhooks are HMAC-signed by default with no config. sse delivery events in the dashboard. every little dx thing i've complained about for years — fixed.
we process 1.2M messages/day across email+SMS+whatsapp. one bill, one dashboard, one api key. our infra meetings are 50% shorter now.
Pricing
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Pricing
Generous free tier.
Pay for what you actually send.
No per-contact fees. No seat taxes. Linear usage-based pricing that undercuts Resend, SendGrid, and Twilio by 30–40% at every tier.
Private beta · pricing preview
We're in private beta. Every send is free today — usage is metered and visible in your dashboard. The tiers below are the planned GA pricing; WhatsApp and SMS line items light up as those channels ship.
Free
For side projects and prototypes.
- 3,000 emails / month
- 100 WhatsApp sessions / month
- 50 SMS segments / month
- Shared IP pool
- Community support
Pro
For developers shipping to production.
- 50,000 emails / month
- 2,500 WhatsApp sessions / month
- 5,000 SMS segments / month
- AI channel routing
- Dedicated IP on request
- Email support · 24h SLA
Scale
For teams with real volume.
- 1M emails / month included
- 50k WhatsApp sessions / month
- 200k SMS segments / month
- Dedicated IPs + managed warmup
- Priority routing queues
- HIPAA BAA · Slack Connect support
Enterprise
For regulated, global, or very large deployments.
- Custom volume commits
- Regional isolation · CMEK
- Custom SLAs · 99.99% uptime
- Dedicated CSM · white-glove onboarding
- SSO, SCIM, audit log exports
- Custom DPA & BAAs
Overage pricing
Go past your plan? Pay-as-you-go kicks in.
No surprise bills. Usage is metered per channel and visible in the dashboard in real time. You can set hard caps to prevent runaway sends.
| $0.40 | per 1,000 sent | |
| WhatsApp session | $0.005 | per session-24h |
| SMS (US) | $0.0075 | per segment |
| SMS (international) | varies | carrier-based |
6 months of Pro, free.
For funded startups (< $5M raised). Get Pro tier free for 6 months, plus priority support and a dedicated slack channel.
ApplyShip messages. Not infrastructure.
Your product needs
messaging that just works.
Invite-only beta · most requests reviewed within 48 hours.