Resend is an email API built for developers, from the team behind React Email. Ours takes the same requests and runs on a full mail platform, so the domain your app sends from also has mailboxes, verified identities and receiving.
Choose Resend if you want the most mature developer tooling today: official SDKs for many languages, first-class React Email support, marketing broadcasts with audience management, and a longer track record of sending at scale. Our Node SDK and SMTP gateway are still rolling out, and we do not offer audiences, contacts or stored templates.
Choose WS Mail if your app and your team share a domain and you would rather manage one provider than two, or if your users are professionals and verified sender identity matters to your recipients.
| Dimension | WS Mail | Resend |
|---|---|---|
| Request and error format | Same fields, error envelope, Idempotency-Key and batch endpoint | The original |
| Webhook signatures | Standard Webhooks (svix-compatible) | Standard Webhooks via svix |
| Official SDKs | REST today; Node SDK rolling out | Many languages |
| React Email | Render to HTML yourself, then send | Built in |
| Marketing audiences and templates | Not offered (broadcast stream with one-click unsubscribe only) | Offered |
| Team mailboxes on the same domain | Full webmail, IMAP and admin console | Not offered |
| Verified sender identity | Credential-checked badge with a public page | Not offered |
| Pricing model | Free API plan (3,000 a month); Developer $10 a month for 50,000 | Free tier, then paid email-API plans |
The request body, the error names and the Idempotency-Key header are the same, and our webhooks are signed so Resend's and svix's verification libraries work unchanged. In most codebases the move is a new base URL, a new key and new webhook secrets. The migration guide lists every field and the few things that differ.
You give up Resend's SDK breadth, React Email integration and marketing tools. You gain one provider for the mail your team reads and the mail your app sends, receiving on the same domain, and a sender identity your recipients can check.
Competitor capabilities described as published by the vendor at the time of writing. Check their current documentation before deciding.
For sending, largely yes: the same request fields, error format, Idempotency-Key header and batch endpoint, and webhook signatures their libraries verify. You change the base URL, the key and the webhook secrets. Audiences, contacts and stored templates are not offered, and React Email output has to be rendered to HTML before sending.
Their SDK is written for their base URL. Our own Node SDK with the same { data, error } contract is rolling out; until then, the REST API works from any language with a plain HTTP request.
Usually because the same domain also needs mailboxes for people, or because verified sender identity matters to your recipients. If neither applies, staying put is a reasonable choice.
The free tier has no expiry and no card, so evaluating us costs nothing but the signup.
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