Resend is an email sending platform for developers, made by the company Resend. It delivers transactional emails (messages that an application sends to one user after an event, such as a password reset or a receipt) and marketing emails (broadcasts to a list of contacts).
An application sends an email with one call to the Resend REST API or through SMTP, the standard protocol for mail; official SDKs exist for Node.js, Python, Ruby, PHP, Go, Rust, Java, Elixir and .NET. Webhooks notify the application's server each time an email is delivered, opened or bounced, or a link is clicked. Templates can be written as React components with react-email, an open-source library from Resend, instead of hand-written HTML tables. To help emails reach the inbox, Resend supports DKIM, SPF and DMARC authentication (DNS records that prove the sender owns the domain), keeps a suppression list of addresses that must not get mail, and sends from regions in four continents. A visual editor, contact lists and analytics serve newsletters.
Resend is a hosted service. A free plan allows 100 emails a day; paid plans are billed monthly by email volume.