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Send your first transactional message in minutes. Comet's REST API works with any language — this guide uses the official TypeScript SDK.

Add Comet to your project with your package manager of choice. The SDK ships with TypeScript types and runs on Node, Bun, and Deno.

npm install comet

Create a client with your API key, then call messages.send. Every request returns an id you can use to track delivery.

import { Comet } from "comet";

const comet = new Comet(process.env.COMET_API_KEY);

const { id } = await comet.messages.send({
  to: "ada@example.com",
  template: "welcome",
});

console.log(`Queued ${id}`);

Reference a template by slug and pass variables — Comet renders the subject and body server-side, so your app never ships copy.

Poll the message endpoint, or subscribe to webhooks for real-time delivery, open, click, and bounce events as they happen.

Verify the signature on each request, then react to the event — here we mark a message delivered in our own database.

app.post("/webhooks/comet", (req, res) => {
  const event = comet.webhooks.verify(req);

  if (event.type === "message.delivered") {
    markDelivered(event.data.id);
  }

  res.sendStatus(200);
});