​
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.