transmitdev

The official TypeScript client for the Transmit API — transactional email and SMS.

npm install transmitdev

Node 18 or newer. ESM and CommonJS both work.

Sending

import { Transmit } from "transmitdev";

const transmit = new Transmit({ apiKey: process.env.TRANSMIT_API_KEY });

const { id } = await transmit.emails.send({
  from: "[email protected]",
  to: "[email protected]",
  subject: "It arrived.",
  text: "Nobody noticed. That's the job.",
});

apiKey falls back to TRANSMIT_API_KEY, and baseUrl to TRANSMIT_BASE_URL, so a deployment can be configured entirely from the environment.

Idempotency

emails.send and sms.send are billed, so the API requires an Idempotency-Key and the client generates one per call. Pass your own to make a retry from your side safe too:

await transmit.emails.send(message, { idempotencyKey: `order-${order.id}` });

Replaying a key returns the original result instead of sending twice.

Errors

Every failure is a TransmitError carrying status, code and details. Catch the subclass you mean to handle:

import { RateLimitError, ValidationError } from "transmitdev";

try {
  await transmit.emails.send(message);
} catch (error) {
  if (error instanceof ValidationError) return fix(error.details);
  if (error instanceof RateLimitError) return retryIn(error.retryAfterSeconds);
  throw error;
}

Rate limits and 5xx are retried automatically — twice by default, with backoff, honouring Retry-After. Creates that the server cannot recognise as a repeat are never retried.

What you can reach

| | | |---|---| | emails | send | | sms | send, list, get | | templates | list, create, get, update, delete | | contacts | list, upsert | | audiences | list, create | | campaigns | list, create | | webhooks | list, create, update, delete | | analytics | get |

Each call is checked against the published spec at api.transmit.dev/openapi.json in CI, so the client cannot name an endpoint the API does not serve.

Migrating from Resend or SendGrid

You do not need this package. Transmit answers POST /emails in Resend's shape and POST /v3/mail/send in SendGrid's — point your existing client at https://api.transmit.dev and change the key.

License

Apache-2.0