Resend vs GrowthBook
The email API for developers — built by the Nodemailer team
vs. Open-source feature flags + experimentation — Warehouse Native
Pricing tiers
Resend
Free
3,000 emails/month, 100 emails/day. 1 custom domain. Ideal for side projects.
Free
Pro — 50k
50,000 emails/month. 10 custom domains. Priority support.
$20/mo
Pro — 100k
100,000 emails/month. 10 custom domains.
$35/mo
Scale — 100k+
Tiered from 100k → 2.5M emails/month. Dedicated IP add-on available.
$90/mo
Scale — 2.5M
2.5M emails/month.
$1150/mo
Enterprise
3M+/month, dedicated IP included, SSO, custom contract.
Custom
GrowthBook
Open Source (Self-Host)
MIT-licensed. Unlimited everything. Community support.
$0 base (usage-based)
Cloud — Starter (Free)
Up to 3 users. Unlimited flags + experiments. Warehouse Native included.
Free
Cloud — Pro
$40/user/month. Up to 50 users. Advanced stats, visual A/B editor, CUPED, sequential testing, bandits.
$40/mo
Cloud — Enterprise
Custom. Unlimited users, SSO/SAML, approval flows, data pipelines, exportable audit logs.
Custom
Self-Host Enterprise
Open Source + Enterprise license. Visual A/B editor, advanced metrics, SSO/SAML, approvals, training.
Custom
Free-tier quotas head-to-head
Comparing free on Resend vs oss on GrowthBook.
| Metric | Resend | GrowthBook |
|---|---|---|
| custom domains | 1 domains | — |
| emails per day | 100 emails/day | — |
| emails per month | 3000 emails/month | — |
Features
Resend · 12 features
- Audiences — Contact list management with custom fields.
- Batch Send — Send up to 100 emails in one API call.
- Broadcasts — Bulk email campaigns with audiences, A/B testing, analytics.
- Dedicated IP — Add-on for high-volume senders. Auto warmup.
- Domains — DKIM/SPF/DMARC auto-verification. Per-domain analytics.
- Idempotency — Prevent duplicate sends with Idempotency-Key header.
- Logs + Analytics — Full email logs, delivery heatmap, events table.
- React Email — OSS library (3M+ downloads) to compose emails in React/JSX.
- Scheduled Send — scheduledAt parameter for future delivery.
- Send API — POST /emails endpoint to send. Supports attachments, scheduled send, idempotency…
- Suppressions — Auto-managed bounce + complaint list. API to add/remove.
- Webhooks — Email lifecycle events: sent, delivered, bounced, complained, opened, clicked.
GrowthBook · 15 features
- Approval Flows — Require reviewer approval on flag changes. Enterprise.
- Audit Logs — Full change history. Exportable on Enterprise.
- Dimensions & Slicing — Break down experiment results by user dimensions.
- Edge SDK Support — Cloudflare Workers, Lambda@Edge, Fastly, Akamai EdgeWorkers, Netlify Edge.
- Experiments — A/B/n with CUPED variance reduction + sequential testing.
- Feature Flags — Boolean + string + number + JSON flags with targeting.
- Feature Reviews (PR-style) — Draft → review → approve flag changes.
- Guardrail Metrics — Auto-monitor key metrics during experiments.
- Metric Catalog — Define + reuse metrics across experiments.
- Multi-Armed Bandits — Adaptive traffic allocation. Pro+.
- Safe Rollouts — Guarded gradual rollouts with automatic rollback.
- SSO / SAML — Enterprise SSO for cloud + self-host EE.
- Sticky Bucketing — User stays in variant even after eligibility changes.
- Visual A/B Test Editor — No-code DOM editor for web experiments. Pro+.
- Warehouse Native — Connect your warehouse + run experiments against your events data.
Developer interfaces
| Kind | Resend | GrowthBook |
|---|---|---|
| CLI | Resend CLI | — |
| SDK | react-email, resend-go, resend-node, resend-php, resend-python, resend-ruby | Edge SDKs (CF Workers / Lambda@Edge / Fastly / Akamai), growthbook-android, growthbook-flutter, growthbook-go, growthbook-java, growthbook-node, growthbook-php, growthbook-python, growthbook-ruby, growthbook-swift, sdk-javascript, sdk-react |
| REST | Resend REST API | GrowthBook REST API |
| OTHER | SMTP Relay, Webhooks (Svix) | Webhooks |
Staxly is an independent catalog of developer platforms. Some links to Resend and GrowthBook may be affiliate links — Staxly may earn a commission if you sign up through them, at no extra cost to you. Pricing is verified against vendor pages at publication time — reconfirm before buying.
Want this comparison in your AI agent's context? Install the free Staxly MCP server.