NodeJS

import { UseSend } from "usesend-js";

const usesend = new UseSend("us_12345");

const usesend = new UseSend("us_12345", "https://app.usesend.com");

usesend.emails.send({
  to: "[email protected]",
  from: "[email protected]",
  subject: "useSend email",
  html: "<p>useSend is the best open source product to send emails</p>",
  text: "useSend is the best open source product to send emails",
  headers: {
    "X-Campaign": "welcome",
  },
});

usesend.contacts
  .create("clzeydgeygff", {
    email: "[email protected]",
    firstName: "Koushik",
    lastName: "KM",
  })

usesend.contacts.update("clzeydgeygff", contactId, {
  firstName: "Koushik",
  lastName: "KM",
});