SMTPfastvsResend
Two developer-first email APIs compared: pricing per volume, contacts and broadcasts, inbound email, MCP and Terraform support, and where each one actually fits.
SMTPfast
A lean email API with transactional sending, inbound receiving, contacts, segments and broadcasts included. Free tier of 3,000 emails/month; paid plans from $9. Ships official SDKs for Node.js, Python, Go and PHP, a Laravel mail driver, a hosted MCP server, an official Terraform provider and an Agent Skill.
Visit websiteResend
The best-known developer email API of the last few years. React Email templates, SDKs for most languages, inbound email, broadcasts, and a hosted MCP server with a broad tool surface. Free tier of 3,000 emails/month (100/day); Pro from $20.
Visit websiteChoose SMTPfast if your bill is volume-driven, you want transactional plus newsletter plus inbound on one plan, or you want a Terraform-managed setup with scoped keys and agent drafts that a person approves. Choose Resend if you need React Email templates, an official SDK for Ruby, Java, Rust or .NET, or a SOC 2 answer for procurement. Both are REST APIs with hosted MCP servers and compatible receiving endpoints, so switching later is mostly DNS records and a changed base URL. Read the verdict
SMTPfast and Resend answer the same question: how does a developer send email through an API without fighting an enterprise dashboard from 2012? Both are API-first, both have generous free tiers of 3,000 emails a month, and both now ship hosted MCP servers so AI agents can send through them. Every number below is stated plainly so you can verify it against both public pricing pages.
The honest difference is shape. Resend is the larger, more mature product with a bigger ecosystem: official SDKs across many languages, React Email for templates, and SOC 2 compliance messaging aimed at scaling startups. SMTPfast is smaller and priced like it wants your side project and your startup's first two years: contacts, segments and broadcasts are included in every tier rather than sold as a separate marketing product, and the paid tiers undercut Resend at most volumes.
This comparison walks the numbers per volume tier, the feature surface (including the newer agent-facing pieces like hosted MCP servers and Terraform support), and the scenarios where each is the right call.
Feature Comparison
- All features20
- Cost5
- Features7
- Ecosystem3
- Operations3
- Security2
strong mixed weak
The ratings differ on 10 of 20 features.
| Feature | SMTPfast | Resend |
|---|---|---|
| Cost | ||
| Free tier | 3,000 emails/mo with no daily cap, 1,000 contacts, 2 broadcasts/mo, no card; invite-gated | 3,000 emails/mo capped at 100/day, 3 domains, instant signup |
| Price at 10,000 emails/mo | $9/mo (Starter, 25k emails, 10,000 contacts) | $20/mo (Pro, includes 50k emails) |
| Price at 50,000 emails/mo | $19/mo (Growth, includes 100k emails) | $20/mo (Pro) |
| Price at 100,000 emails/mo | $19/mo (Growth, 100k emails, 50,000 contacts) | $35/mo (Pro) |
| Price at 200,000 emails/mo | $49/mo (Scale, 300k emails, 150,000 contacts) | $125/mo (Pro plus pay-as-you-go) or $160/mo (Scale) |
| Features | ||
| Transactional sending API | REST API with idempotency, batch sending, scheduling, inline cid images, automatic plain-text part, share links for sent emails | REST API, batch sending, scheduling, React Email rendering |
| SMTP relay | SMTP interface available alongside the REST API | SMTP interface (smtp.resend.com) alongside the REST API |
| Contacts, segments and broadcasts | Included in every plan: 1,000 contacts on Free, 10,000 on Starter, 50,000 on Growth, 150,000 on Scale | Audiences and Broadcasts, with marketing priced separately by contacts: $40/mo for 5k, $250/mo for 50k, $650/mo for 150k |
| Newsletter signup forms | Hosted signup forms that feed contacts and segments directly | No hosted forms; add contacts via API, CSV import or manually |
| Inbound email | Per-domain receiving on paid plans: one MX record, dashboard Inbound page, Resend-compatible receiving API, email.received webhook, 30-day retention, virus and spam verdicts | Inbound receiving with webhooks and a receiving API |
| Inboxes with threads | Inboxes on your own domain: threads, labels, and drafts a person approves before an agent's reply goes out (paid plans) | Inboxes API in private beta |
| Hosted templates | Hosted templates with variables, live preview and 10 starters; Resend-compatible Templates API | Templates API and editor, plus React Email components |
| Ecosystem | ||
| Official SDKs | Official Node.js/TypeScript, Python (sync and async), Go and PHP SDKs plus a Laravel mail driver, generated from the OpenAPI spec, with retries, an automatic Idempotency-Key on sends, typed errors, pagination and webhook signature checks. Resend's SDKs also work with SMTPfast's Resend-compatible endpoints | Official SDKs for Node.js, PHP, Python, Ruby, Go, Java, Rust and .NET |
| Hosted MCP server for AI agents | Yes, /api/mcp, 104 scoped tools covering almost the whole API, OAuth or API key | Yes, mcp.resend.com, broad tool surface, OAuth or API key |
| Public changelog | /changelog with every customer-visible change since launch | Detailed changelog, several entries a week |
| Operations | ||
| Infrastructure as code | Official Terraform provider | Community Terraform provider |
| Deliverability protection | Staged warm-up, suppression management, URL reputation scanning, and broadcasts that pause themselves on a complaint or bounce spike | Managed IP pools, suppression management, deliverability tooling |
| Team workspaces | Teams with roles, seats, audit log, shared domains and owner-level billing | Team members per workspace on paid plans |
| Security | ||
| Compliance posture | Standard practices; no formal certification published | SOC 2 Type II messaging for security reviews |
| API key scopes | Per-key scopes chosen in the dashboard (send, read, domains, contacts, inbound, ...) and editable later | Full access or sending-only keys, optionally limited to one domain |
Cost
Features
Ecosystem
Operations
Security
Pros and Cons
Strengths
- Lower price at every paid step: 25,000 emails for $9/month, 100,000 for $19/month, 300,000 for $49/month
- Contacts, segments and broadcasts included in every tier, no separate marketing add-on
- Hosted newsletter signup forms included, no separate form tool needed
- Hosted MCP server with scoped tools plus an official Terraform provider
- Free tier includes 3,000 emails/month, 1,000 contacts and broadcasts, no credit card
- Gradual sending warm-up for new accounts protects deliverability by default
Weaknesses
- Free tier is invite-gated: you request access or pay to skip the queue
- Official SDKs cover only Node.js, Python, Go and PHP (plus a Laravel mail driver), and they are new (first released in October 2026); other languages call the REST API directly or use a Resend SDK pointed at SMTPfast
- Inbound email only on paid plans
- Younger product with a smaller community and template ecosystem
Strengths
- Mature ecosystem: official SDKs, React Email, extensive docs and examples
- Inbound email receiving, not just sending
- Hosted MCP server with a broad tool surface and OAuth sign-in for web clients
- Instant free tier signup, no invite queue
- SOC 2 compliance posture aimed at companies with security review processes
Weaknesses
- More expensive at volume: Pro is $35 for 100,000 emails, extra emails cost $0.90 per 1,000 once you turn on pay-as-you-go, and Scale starts at $90
- Free tier capped at 100 emails/day, which blocks bursty use
- Broadcast/audience features grew out of transactional and are priced accordingly at scale
Which One Fits You?
Each situation below points to one tool. Tick the ones that match your team.
Tick the situations that apply to you.
Use Cases
A side project or early startup that also needs a newsletter
SMTPfast includes contacts, segments and broadcasts in every tier including free, so transactional plus newsletter runs on one bill from day one. Starter covers 10,000 contacts for $9 and Growth 50,000 for $19, where Resend prices marketing contacts separately ($40 a month for 5,000, $250 for 50,000).
A product built on React that lives on polished email templates
React Email plus Resend's SDKs is the smoothest template workflow in the industry. If your team already thinks in components, nothing else feels as native.
High-volume transactional sending on a budget
At 100,000 emails a month the gap is $19 versus $35 on Resend Pro. At 200,000 it is $49 versus $125 on Resend Pro with pay-as-you-go turned on, or $160 on Scale. If email volume grows faster than revenue, the pricing curve matters more than ecosystem width.
You need to receive email, not just send it
Both receive email now: Resend with inbound webhooks, SMTPfast with per-domain receiving on paid plans, a Resend-compatible receiving API and an email.received webhook. If you already integrate Resend receiving, the SMTPfast endpoints and objects have the same shape.
AI agents sending email on your behalf
Both ship hosted MCP servers, which puts them ahead of nearly every other email provider, and both now cover most of their APIs. SMTPfast keeps API keys and team members out of the agent's reach, and its inboxes let an agent write drafts that a person approves before anything is sent. Pick by how much you want the agent to do on its own.
An enterprise security review stands between you and shipping
Resend's SOC 2 posture and larger track record clear procurement conversations that a younger product will get stuck in.
Verdict
Resend is the safer default for teams that want the biggest ecosystem: official SDKs in more languages, React Email, and a compliance story for security reviews. SMTPfast is the value pick and the simpler one to reason about: contacts and broadcasts included everywhere, inbound email on paid plans with a Resend-compatible receiving API, half the price of Resend Pro at 100k emails a month ($19 against $35), scoped API keys, official SDKs for Node.js, Python, Go and PHP plus a Laravel mail driver, a scoped hosted MCP server, and an official Terraform provider. If you need React Email or a SOC 2 answer, pick Resend. If your bill is driven by volume, or you want transactional, newsletter and inbound in one product without a marketing-tier upsell, SMTPfast costs less at every paid step and does all three.
Our Recommendation
Choose SMTPfast if your bill is volume-driven, you want transactional plus newsletter plus inbound on one plan, or you want a Terraform-managed setup with scoped keys and agent drafts that a person approves. Choose Resend if you need React Email templates, an official SDK for Ruby, Java, Rust or .NET, or a SOC 2 answer for procurement. Both are REST APIs with hosted MCP servers and compatible receiving endpoints, so switching later is mostly DNS records and a changed base URL.
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