API & SMTP
for transactional email

Send transactional emails via REST API or SMTP relay. Webhooks for delivery events, official SDKs, and comprehensive documentation.

Integrate in minutes

Everything you need to send and track transactional emails from your application.

REST API

Clean, well-documented REST API for sending emails, managing contacts, and querying analytics. JSON request and response format.

SMTP relay

Standard SMTP relay with TLS encryption. Drop-in replacement for any SMTP provider. Just update your credentials.

Webhooks

Real-time webhook notifications for delivery, opens, clicks, bounces, complaints, and unsubscribes.

Official SDKs

First-party SDKs for PHP, Node.js, Python, Ruby, and Go. Install from your package manager and start sending in minutes.

Authentication

API key authentication with scoped permissions. DKIM, SPF, and DMARC setup for your sending domains.

Delivery analytics

Query delivery status, open rates, click rates, and bounce data via the API. Build custom dashboards and reports.

Built for reliability

Enterprise-grade features for teams that depend on email delivery.

Template API
Create, manage, and render email templates via the API. Use Handlebars syntax for dynamic content and variables.
Batch sending
Send to multiple recipients in a single API call. Each recipient gets a personalized version of the email.
Inbound email
Parse incoming emails with inbound routing. Forward replies and incoming messages to your app via webhook.
Webhook signing
All webhooks are signed with HMAC-SHA256. Verify the signature to ensure events are authentic.
Rate limiting
Generous rate limits with clear headers. Automatic retry with exponential backoff in all SDKs.
99.9% uptime SLA
Enterprise-grade infrastructure with redundancy across multiple regions. Status page and incident notifications.

Loved by developers and teams

See how teams are using SendKit to power their email infrastructure.

We switched to SendKit for our transactional emails and saw deliverability jump from 94% to 99.2%. The API is clean, the docs are great, and we were integrated in under an hour.

S
Sarah Chen
CTO at Launchpad

SendKit's SMTP relay was the easiest migration we've done. We just swapped the credentials and everything worked. The real-time webhooks for bounce handling saved us weeks of work.

M
Marcus Rodriguez
Founder at Stackflow

The campaign builder is surprisingly powerful for a developer-focused tool. We run our entire newsletter and drip sequences through SendKit now. The analytics are exactly what we needed.

E
Emily Park
Head of Growth at Metric

What sold us was the pricing transparency. No per-contact fees, no surprise charges. We send 500K transactional emails a month and the cost is predictable every single time.

J
James Okafor
Lead Engineer at Paystream

We needed both transactional and marketing email in one platform. SendKit handles our password resets, order confirmations, AND our weekly newsletter. One dashboard, one bill, zero headaches.

A
Ana Soares
Co-founder at Buildkit

The automation workflows are a game-changer. We set up onboarding sequences that trigger based on user events via the API. Our activation rate improved 40% in the first month.

D
David Kim
DevOps at CloudBase

We switched to SendKit for our transactional emails and saw deliverability jump from 94% to 99.2%. The API is clean, the docs are great, and we were integrated in under an hour.

S
Sarah Chen
CTO at Launchpad

SendKit's SMTP relay was the easiest migration we've done. We just swapped the credentials and everything worked. The real-time webhooks for bounce handling saved us weeks of work.

M
Marcus Rodriguez
Founder at Stackflow

The campaign builder is surprisingly powerful for a developer-focused tool. We run our entire newsletter and drip sequences through SendKit now. The analytics are exactly what we needed.

E
Emily Park
Head of Growth at Metric

What sold us was the pricing transparency. No per-contact fees, no surprise charges. We send 500K transactional emails a month and the cost is predictable every single time.

J
James Okafor
Lead Engineer at Paystream

We needed both transactional and marketing email in one platform. SendKit handles our password resets, order confirmations, AND our weekly newsletter. One dashboard, one bill, zero headaches.

A
Ana Soares
Co-founder at Buildkit

The automation workflows are a game-changer. We set up onboarding sequences that trigger based on user events via the API. Our activation rate improved 40% in the first month.

D
David Kim
DevOps at CloudBase

Ready to send better emails?

Start for free and scale as you grow. No credit card required. Get up and running in minutes with our API and SMTP relay.