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Note: Resend integration is available on the Builder plan and above. If you’re on the Free plan, you need to upgrade your app to use backend functions.

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Step-by-step setup

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Part 1: The Resend side

If you already have your Resend API keys, you can skip ahead to “Part 2 - The Base44 side” setup
1

Create a Resend account

The Resend Domains page with no domains added and the Add Domain button

Adding your domain in Resend

If you don’t already have one:
  1. Go to Resend domains
  2. Sign up and add your domain
2

Verify your domain

After adding your domain
  1. Follow the DNS instructions provided by Resend to complete domain verification. You’ll be given DNS records (TXT, MX) to add via your own DNS provider.
  2. These help prevent your emails from being flagged as spam.
Resend requires an MX record on a subdomain host such as send.yourdomain.com, not on your root domain. If you bought your domain through Base44, MX records are set for your root domain by the email provider you connect and cannot be edited by hand, so contact support with the host, value, and priority for the subdomain record and we will add it for you.
Tip: You can use a subdomain like updates.yourdomain.com or mail.yourdomain.com instead of your main domain. This helps isolate your email sending reputation and can reduce the chance of deliverability issues affecting your primary domain.
3

Create your Resend API key

The Resend API Keys page with no keys yet and the Create API Key button

Creating a Resend API key

  1. Go to the API Keys page
  2. Click on “Generate API key”
  3. Copy and save the key somewhere secure, but also keep it handy. You’ll need to paste it into Base44 in the next step.

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Part 2: The Base44 side

Once you have your Resend API keys, there are 2 ways to use this integration in Base44. Click the option below to expand and view the instructions.

Option 1: Creating an app from scratch (preferred)

  1. Head over to the integrations catalog page
    Make sure you’re logged into Base44 to view this page
    Base44 home prompt page with Integrations outlined in the top navigation

    Opening the Integrations catalog

  2. Find Resend and click “Use this integration”
    The Resend integration page with Use this integration highlighted in the Get Started panel

    Adding the Resend integration

  3. When prompted, paste your API key from Step 3. Your app is now connected to Resend.
    The Resend integration card with the RESEND_API_KEY field and a Missing required keys warning

    Pasting your Resend API key

  4. Type out your idea / prompt into the AI chat box to build your app
    “Build me an app to create and send welcome emails when someone signs up.”
    Base44’s AI walks you through setting it up.

Option 2: Working with an existing app

If you’re working in an existing app, you can use the chat to ask:
“Add the Resend integration to my app. Prompt me for the API key and send a welcome email when someone subscribes.”
The AI chat then walks you through the steps to set up this integration and prompts you for your API keys.

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Common use cases for the Base44 x Resend integration

Here are some examples of how Resend can be used in your Base44 app:
  • Welcome emails when someone signs up
  • Order confirmations or status updates
  • Internal team alerts when forms are submitted
  • Reminder emails for actions left incomplete
  • Newsletter campaigns for subscribers or app users
  • Survey or feedback requests after key actions
  • Trigger-based updates to app users or admins

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FAQ

Resend is a modern email API platform. It helps developers send transactional and marketing emails easily, with a focus on deliverability and ease of use.
No. The free tier lets you send emails from a verified domain, with up to 3,000 emails per month and up to 1,000 marketing contacts. See Resend’s pricing for current limits.
Use Resend’s Audiences to:
  • Add contacts via CSV, manually, or via the API.
  • Automatically manage unsubscribes with Resend’s built-in link.
Unsubscribes are processed automatically:
  • You must include an unsubscribe link in all broadcast emails.
  • Resend removes people who unsubscribe from the audience you sent to.
  • This ensures compliance with laws like CAN-SPAM and GDPR.
Yes, manually:
  1. Send a confirmation email after form submission.
  2. Include a link for people to click.
  3. Only add people to your audience after they confirm.
A few common reasons:
  • Your domain isn’t verified
  • Missing plain-text version
  • Using a generic sender (e.g., onboarding@resend.dev)
  • No unsubscribe link in marketing emails
Use Resend’s Deliverability Insights to get suggestions based on your email setup.
Yes, you can use tools like React Email, which is an open-source library for building styled emails with React components. If you use Base44’s built-in emails instead, you can design them in Emails in your dashboard. Learn more about designing your app’s emails.
Yes, Resend supports both types of emails:
  • Transactional emails, like account confirmations, password resets, and real-time notifications
Marketing emails, such as newsletters and promotional campaigns, sent using the Broadcast tool and Audiences