9 Best Free Transactional Email APIs for Node.js (2026), Tested

import { LoopsClient } from 'loops';

const loops = new LoopsClient(process.env.LOOPS_API_KEY);
await loops.sendTransactionalEmail({
  transactionalId: 'your-transactional-id',
  email: 'user@example.com',
  dataVariables: { name: 'Ada' },
});

import { MailtrapClient } from 'mailtrap';

const client = new MailtrapClient({ token: process.env.MAILTRAP_TOKEN });
await client.send({
  from: { email: 'you@yourdomain.com' },
  to: [{ email: 'user@example.com' }],
  subject: 'Hello',
  text: 'It works.',
});

import { Resend } from 'resend';

const resend = new Resend(process.env.RESEND_API_KEY);
await resend.emails.send({
  from: 'you@yourdomain.com',
  to: 'user@example.com',
  subject: 'Hello',
  html: '<p>It works.</p>',
});

import nodemailer from 'nodemailer';

const transport = nodemailer.createTransport({
  host: 'mail.smtp2go.com',
  port: 587,
  auth: { user: process.env.SMTP_USER, pass: process.env.SMTP_PASS },
});
await transport.sendMail({
  from: 'you@yourdomain.com',
  to: 'user@example.com',
  subject: 'Hello',
  text: 'It works.',
});