Resend vs SendGrid

What each vendor charges at 50,000, 100,000 and 1.5 million emails

At 50,000 emails a month Resend's pricing page reads Pro at $20, and the SendGrid Email API pricing page reads Essentials at $19.95. Over a year that is $240 against $239.40, so the decision at this size cannot rest on price.

At 100,000 emails Resend Pro reads $35 and SendGrid Essentials reads $34.95. The higher tiers match nearly as closely: Resend Scale is $90 and SendGrid Pro is $89.95 (yearly $1,080 against $1,079.40). The difference is what the higher plan carries. SendGrid Pro lists dedicated IPs. Resend Scale lists 1,000 domains and a dedicated Slack channel, with a dedicated IP as a $30-a-month add-on for customers sending more than 3,000 emails a day. A team that wants its own IP therefore pays $89.95 on SendGrid and $120 on Resend at 100,000 emails.

At 1.5 million emails SendGrid Pro is $799 and Resend Scale is $825: SendGrid is $26 a month cheaper, $312 a year. Further up, SendGrid Pro reads $1,099 at 2,500,000 and Resend Scale reads $1,150, a $51 monthly gap and $612 a year. In the middle, SendGrid also publishes $249 at 300,000 and $499 at 700,000, while Resend's published stops are $160 at 200,000, $350 at 500,000 and $650 at 1,000,000, so those volumes cannot be compared like for like. Only at 1.5 million and above does SendGrid have a consistent, small price edge.

The send call: idempotency, scheduling and bulk limits

Resend's send email reference lets you attach an Idempotency-Key to each request, so a client that times out and retries will not send twice; keys last 24 hours. It also offers scheduled_at in natural language, template sends by id or alias with variables, and tags. The batch endpoint sends up to 100 emails per call and does not accept attachments. The default limit is 10 requests per second per team.

SendGrid's Mail Send reference centres on personalizations: one request can hold up to 1,000 of them, each with its own recipients and template data, which is why SendGrid needs far fewer requests for a large fan-out. A send is accepted with a 202. send_at takes a Unix timestamp but never more than 72 hours ahead, so a reminder that must go out a week from now needs your own scheduler. Dynamic templates use IDs starting with d-, and their Handlebars supports conditions and loops, as the dynamic templates guide describes.

For a monthly invoice run to 40,000 customers, SendGrid can do the job in 40 requests of 1,000 personalizations, while Resend needs 400 batch calls of 100, 40 seconds of calls at the default limit. Neither is hard, but the loop looks different, and Resend's loop needs a queue.

Webhooks: Svix on one side, ECDSA or OAuth on the other

Resend's webhooks use Svix. The verification guide says to read the svix-id, svix-timestamp and svix-signature headers and pass them, with the raw body and your endpoint's signing secret, to the Resend SDK verify method or to the Svix package. A failure throws. The retries page lists eight attempts over more than 27 hours, lets you replay both failed and successful messages from the dashboard, and disables an endpoint that keeps failing, with an email to your team.

SendGrid offers two methods that can run together. The security features guide describes an ECDSA signature in the X-Twilio-Email-Event-Webhook-Signature header with a timestamp in X-Twilio-Email-Event-Webhook-Timestamp; you hash the timestamp plus the raw payload bytes with SHA-256 and check it against the public key, using the helper in one of seven SendGrid libraries. The other is OAuth 2.0 with client credentials: SendGrid fetches a token and sends it in an Authorization header, and you verify it. The guide warns that converting the payload to a JSON string can alter the characters that were signed.

SendGrid retries a failed event for up to 24 hours on a rolling basis, does not follow redirects, and gives each event an sg_event_id for deduplication. Both vendors want raw bytes, so the common failure is a framework that parses the body first. With Resend you get a library call and a replay button; with SendGrid you get two options, which suits a security team that already runs OAuth for machine-to-machine traffic.

Inbound mail and suppression handling

Resend receiving works at a Resend-managed id.resend.app address or at your own domain after adding an MX record, per the receiving guide. It parses the message, posts to your endpoint, and lets you fetch HTML, text and headers by API, with attachments as temporary download URLs.

SendGrid's Inbound Parse points an MX record at mx.sendgrid.net (priority 10) on a hostname used for nothing else, associates it with your URL, and posts multipart/form-data. The total message size limit is 30 MB. A spam score and report are added for messages up to 2.5 MB, and Send Raw returns the full MIME. If the receiving domain is also your authenticated sending domain, Automatic Security on the authenticated domain must be turned off, otherwise messages loop between the CNAME and MX servers.

For suppression, Resend keeps one team-wide suppression list with three origins (bounce, complaint, manual); the API adds or removes up to 100 addresses per call. SendGrid keeps separate lists, as its suppressions documentation shows: blocks (temporary, not suppressed), bounces, invalid emails, spam reports and global unsubscribes. The Mail Send API can also bypass list management for a request. The separate lists give finer control and more to export during a migration.

Marketing sends: Resend Marketing tab against Marketing Campaigns

Resend's Marketing tab prices by contacts: free at 1,000 contacts with unlimited broadcasts, 10,000 automation runs and 3 segments, then $40 at 5,000, $80 at 10,000, $180 at 25,000, $250 at 50,000 and $450 at 100,000. Broadcasts go to a segment and topics let recipients choose which categories they receive.

SendGrid's Marketing Campaigns has a free plan for up to 2,000 contacts and 6,000 emails a month, Basic from $15 for up to 100,000 contacts and 300,000 emails, and Advanced from $60 for up to 200,000 contacts and 1,000,000 emails, with dedicated IP access. Because the starting prices are minimums, move the selector to your contact count before comparing against Resend's readouts. For a list of 1,800 contacts the SendGrid free plan is enough, while Resend's free Marketing plan stops at 1,000.

Moving from SendGrid to Resend

If you used Marketing Campaigns, export contacts as CSV, create segments in Resend, and map SendGrid's unsubscribe groups to topics. The group_unsubscribe events already stored in your database show which groups you used.

1. Add your domain to Resend and publish the records. Resend suggests sending from subdomains, so give transactional and newsletter mail separate ones. Keep SendGrid live while DNS propagates.
2. Swap credentials: an API key in the Bearer header, or smtp.resend.com with the username resend and the key as the password in place of SendGrid's apikey username.
3. Translate each Mail Send payload. Personalizations become one email per recipient (or up to 100 per batch call), dynamic_template_data becomes template variables, categories and custom args become tags or headers, and send_at becomes scheduled_at. Remember reserved variable names: FIRST_NAME, LAST_NAME, EMAIL and UNSUBSCRIBE_URL.
4. Rebuild templates. SendGrid dynamic templates use Handlebars conditions and loops; the Resend template pages read describe variable substitution, so move conditional blocks into your code or render HTML with React or another renderer before sending.
5. Replace the ECDSA or OAuth check with Svix verification on the raw body. Map delivered to email.delivered, deferred to email.delivery_delayed, bounce to email.bounced and spam report to email.complained, then check how your handling of dropped events maps to email.suppressed.
6. Export SendGrid's bounces (up to 500 per API query, with offsets) and global unsubscribes, and add them to Resend's suppression list. Convert Inbound Parse to Resend receiving by moving the MX record and rewriting the handler to fetch the body by API.
7. Add Idempotency-Key headers to retried sends, and queue bulk jobs to respect 10 requests per second. Send password resets first, watch webhook events for a week, then move the rest.

Moving from Resend to SendGrid

1. Create an API key with Mail Send permission, verify the sender identity and authenticated domain, and keep Resend's records in place until the cutover.
2. For SMTP use smtp.sendgrid.net on port 587 with the username apikey. Per-message settings travel in the X-SMTPAPI header.
3. Rewrite the send call for POST /v3/mail/send. Put recipients and per-recipient data in personalizations (up to 1,000 per request), and move template sends to a dynamic template with a d- ID and dynamic_template_data. Render React Email components to HTML yourself, because there is no react parameter.
4. Plan around send_at: SendGrid will not schedule more than 72 hours ahead, so any Resend scheduled_at further out needs your own scheduler. The Mail Send page read lists no idempotency header, so keep a send ledger before retrying.
5. Replace Svix verification with the ECDSA check on the raw bytes, or use OAuth 2.0 client credentials. Map email.bounced to bounce, email.delivery_delayed to deferred, email.complained to spam report, and deduplicate on sg_event_id.
6. Move suppressions with the Global Suppressions API, and receiving with Inbound Parse: an MX record to mx.sendgrid.net at priority 10 on a dedicated hostname, which the SendGrid docs say not to change afterwards.
7. If you used Resend's Marketing tab, load contacts into Marketing Campaigns and check the plan selector at your contact count. Choose the Pro Email API plan if you want dedicated IPs included.