Sending email with Attachments using Resend API in Node.js

Resend is a developer-friendly email provider using which you can send transactional emails easily.

In this post, let's see how to add file attachments to the email.

The only dependency we've is getting the API key which you can easily get from Resend dashboard

As per the docs, we can send attachments in two ways.

Directly giving hosted file's URL
Passing the content of the file as a buffer/string

Passing the attachment file as a URL

It's straight forward, pass the path to the hosted file as an URL (make sure it's public) in attachments[].path

{
  "from": "onboarding@resend.dev",
  "to": "example@gmail.com",
  "subject": "An email with file Attachment",
  "text": "It works!",
  "attachments":[
    {
      "filename":"example.jpg",
      "path":"https://nesin.io/_next/image?url=%2Fstatic%2Fimages%2FAshikNesin.jpg&w=384&q=75"

    }
  ]
}

It'll take care of the rest

Passing the content of the file as a Buffer

First, we'll be reading the file as a buffer and then pass it to the API call

npm install node-fetch

import fetch from "node-fetch";

const RESEND_AUTH_KEY = process.env.RESEND_AUTH_KEY

const fileBuffer = await fs.readFile('example.png');

const payload = {
    "from": "onboarding@resend.dev",
    "to": "example@gmail.com",
    "subject": "A email with file Attachment",
    "text": "It works!",
    "attachments": [
        {
            filename: "example.png",
            content: fileBuffer
        }
    ]
  }

const requestOptions = {
  method: 'POST',
  headers: {
    "Content-Type": "application/json",
    "Authorization": `Bearer ${RESEND_AUTH_KEY}`
  },
  body: JSON.stringify(payload)
};

fetch("https://api.resend.com/emails", requestOptions)
  .then(response => response.text())
  .then(result => console.log(result))
  .catch(error => console.log('error', error));

Happy sending emails!