Prerequisites

To get the most out of this guide, you’ll need to:

1. Install

Get the Resend Ruby SDK.

gem install resend

2. Send email using HTML

The easiest way to send an email is by using the html parameter.

index.rb
require "sinatra"
require "resend"

set :port, 5000
set :bind, "0.0.0.0"

Resend.api_key = ENV["RESEND_API_KEY"]

get "/" do

  content_type :json

  params = {
    from: 'Acme <onboarding@resend.dev>',
    to: ['delivered@resend.dev'],
    subject: 'hello world',
    html: '<strong>it works!</strong>',
  }

  Resend::Emails.send(params).to_hash.to_json
end

3. Try it yourself

Sinatra Example

See the full source code.