---
title: Introduction
description: Choose a sender for the channel and a transport for the provider.
icon: Compass
source: "README.md"
---

sently is the channel-delivery layer for email, SMS, WhatsApp, and push (Web Push or FCM).
Choose a channel sender first, then attach a provider transport — so adding SMS or push later does not invent a new error and retry model in your app.

<Callout title="The one rule">Use `createMailer`, `createSmsSender`, `createWhatsAppSender`, or `createPushSender` in app code; swap transports when provider configuration changes.</Callout>

<Steps>
  <Step title="Install the package">

```bash
bun add sently
```

  </Step>
  <Step title="Send with a channel sender">

```ts
import { createMailer } from "sently/mailer";
import { ResendTransport } from "sently/transports/resend";

const mailer = await createMailer({
  transport: new ResendTransport({
    apiKey: process.env.RESEND_API_KEY!,
  }),
});

await mailer.send({
  from: "hello@example.com",
  to: "person@example.com",
  subject: "Welcome",
  text: "Thanks for joining.",
});
```

  </Step>
</Steps>

## Choose a channel

| Channel | Factory | Delivery contract |
| --- | --- | --- |
| Email | `createMailer` / `createSMTPMailer` | `Transport` |
| SMS | `createSmsSender` | `SmsTransport` |
| WhatsApp | `createWhatsAppSender` | `WhatsAppTransport` |
| Push | `createPushSender` | `PushTransport` |

Email factories are asynchronous. The other channel factories return their sender synchronously; all send operations are asynchronous.

## Troubleshooting

<Accordions>
  <Accordion title="Which factory should I use for SMTP?">
    Use `createSMTPMailer` with SMTP host, port, and authentication. Use `createMailer` when you already have a transport.
  </Accordion>
  <Accordion title="Can I replace a provider later?">
    Yes. Keep your channel sender calls and construct it with another transport that implements the same channel contract.
  </Accordion>
</Accordions>

## Learn more

- [Install sently](./installation)
- [Choose an entrypoint](./entrypoints)
- [Stability policy](./stability)
- [Support matrix](./support-matrix)
- [Compare](/docs/guides/compare)
- [Explore channels](../channels)

## Next

<Cards>
  <Card title="Email channel" href="/docs/channels/email" />
  <Card title="Support matrix" href="/docs/get-started/support-matrix" />
  <Card title="Channels" href="/docs/channels" />
</Cards>