Email infrastructure,
done right.
Transactional and marketing email with deliverability, templates, idempotency, and real-time telemetry built in. One SDK replaces your entire email stack.
import { Send0 } from 'send0';
const send0 = new Send0(process.env.SEND0_API_KEY!);
await send0.emails.send({
from: 'hello@yourdomain.com',
to: 'user@example.com',
subject: 'Welcome to Acme',
html: '<h1>Welcome!</h1>',
tags: [{ name: 'category', value: 'welcome' }],
});Capabilities
Everything you need to ship email,
nothing you have to glue together.
Built for teams who care about deliverability, developer experience, and being able to reason about their email system at 3am.
Transactional & marketing queues
Separate priority queues keep OTPs, receipts, and password resets on a lane that is never blocked by marketing sends.
DKIM, SPF, DMARC on rails
Add a domain, copy three DNS records, ship. We continuously re-check records and alert you before your reputation slips.
Suppression & bounce handling
Hard bounces, spam complaints, and unsubscribes are suppressed globally and per-workspace. Your sender score stays intact.
Templates with variables
Handlebars-style templates with {{variables}}, version history, live preview, and per-send overrides.
Signed webhooks
Real-time delivered / bounced / complained / opened / clicked events. Every payload signed with HMAC-SHA256 and replay-safe.
Test mode keys
sk_test_ keys give you full API parity with zero real sends. Perfect for CI, staging, and local development.
Idempotency keys
Safely retry any POST /emails call. Duplicate requests return the original email — your users never get the same email twice.
Tags & metadata
Attach structured tags and metadata to every send. Filter events, group analytics, and drive your own reporting downstream.
Dedicated IPs (on demand)
Grow into your own IP with automatic warmup. Stay on the shared pool while you scale, switch the moment it makes sense.
How a send works
From POST /v1/emails to your customer's inbox in under two seconds.
API request
Your code hits POST /v1/emails. We validate the payload, look up the sender domain, and enqueue the send.
Suppression + policy checks
Every recipient is checked against your suppression list, workspace quotas, and per-domain reputation rules before we accept the job.
MTA dispatch
The message is signed with DKIM, enriched with unsubscribe headers and List-ID, then dispatched to our MTA pool.
Delivery + telemetry
Delivery status, opens, clicks, bounces, and complaints stream back as signed webhooks and into the dashboard in real time.
Developer experience
Write less glue code.
The SDK is a thin wrapper over the REST API. Everything you can do from curl, you can do from TypeScript, Python, or Go — with the same names, the same shapes, and the same errors.
await send0.emails.send({
from: 'receipts@acme.com',
to: 'jane@example.com',
subject: 'Your receipt from Acme',
html: renderReceipt(order),
tags: [
{ name: 'type', value: 'receipt' },
{ name: 'order_id', value: order.id },
],
}, {
idempotencyKey: `receipt-${order.id}`,
});Included in every plan
No usage gates on
the things that matter.
We don't hide webhooks, dedicated IPs, or team seats behind enterprise pricing. Everything below ships with the free tier.
- Unlimited domains & sending identities
- 3,000 emails / month on free tier
- Transactional + marketing priority queues
- Signed webhooks (delivered, bounced, complained, opened, clicked)
- Idempotent POST /emails retries
- Suppression list + one-click unsubscribe
- Real-time logs with 30-day retention
- DKIM / SPF / DMARC health monitoring
- Team workspaces + scoped API keys
- Audit log of every API call
Deliverability you can
actually point a graph at.
Every send is scored against Gmail, Outlook, Yahoo, and Apple inbox placement. We publish aggregate numbers and expose your own deliverability score in the dashboard.
Start shipping
Send your first email in
under five minutes.
Install the SDK, drop in a test key, and watch the event stream light up. Move to sk_live_ the moment you're happy.
3,000 emails / month free · no credit card · cancel anytime