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Email APIs2026 Guide

Resend vs SendGrid vs Postmark 2026

The definitive comparison of transactional email APIs for SaaS and developers. Compare pricing, deliverability, developer experience, and choose the right email service for your stack.

14 min read
Transactional email focus
Published February 2026

Quick Verdict

Resend
Resend

Best developer experience: React Email, modern API, clean docs. Great free tier (100 emails/day).

Best DXReact Email
SendGrid
SendGrid

Best for scale and enterprise: marketing + transactional, billions of emails, proven at scale.

ScaleMarketing + Tx
Postmark
Postmark

Best deliverability in the industry: 99%+ inbox rate, delivery under 1 second. Transactional only.

DeliverabilitySpeed

Provider Overview

Each provider serves different needs. Here's a quick breakdown of Resend, SendGrid, and Postmark.

Best DX
Resend

Resend

Modern email API for developers

Free → $20/mo Pro

starting / main plan

  • React Email (JSX templates)
  • REST API & SMTP
  • 100 emails/day free
  • SOC 2 Type II, GDPR
  • Open/link tracking, batch sending
  • Beautiful documentation

Best for: Developers who want the best DX and modern tooling (React Email)

SendGrid

SendGrid

Email delivery at scale (Twilio)

From $19.95/mo

starting / main plan

  • Marketing + transactional
  • Dynamic templates
  • Email validation, analytics
  • 60-day free trial (100/day)
  • Enterprise proven, billions sent
  • Dedicated IP on Pro

Best for: Teams needing marketing + transactional and high volume

Best Deliverability
Postmark

Postmark

Transactional email, best deliverability

$15/mo Basic (10K)

starting / main plan

  • 99%+ inbox rate
  • Delivery in under 1 second
  • 45-day retention (Basic)
  • Transactional only (no marketing)
  • Inbound email (Pro+)
  • DMARC monitoring add-on

Best for: Teams where deliverability and speed matter most

Pricing Breakdown

Understanding the true cost is crucial. Here's how free tiers and paid plans compare.

Resend

Resend

Free / Trial100/day free
Pro / Basic$20/mo (50K)
Scale$90/mo (100K)
Dedicated IP$30/mo add-on
Retention1–7 days

Additional:

  • 10 domains, 10 webhooks (Pro)
  • 1,000 domains (Scale)
  • Dedicated Slack (Scale)
SendGrid

SendGrid

Free / Trial60-day trial
Pro / Basic$19.95 (100K)
Scale$89.95 (1.5M)
Dedicated IPIncluded Pro+
RetentionVaries

Additional:

  • Free plan retired May 2025
  • 2,500 validations (Pro)
  • Premier: custom pricing
Postmark

Postmark

Free / Trial100/mo (dev)
Pro / Basic$15 (10K)
Scale$75 (100K)
Dedicated IP$50/mo
Retention45 days (Basic)

Additional:

  • Pro: $16.50 (inbound)
  • Platform: $18 (team)
  • DMARC: $14+/mo

Feature Comparison

A detailed breakdown of what each provider offers.

Feature
Resend
SendGrid
Postmark

Core

REST API
SMTP
Webhooks
Batch sending
Open / link tracking

Templates & DX

React Email / JSX
Dynamic templates
Simple
Template versioning
Documentation quality
Excellent
Good
Good

Deliverability & Compliance

SOC 2 Type II
GDPR compliant
Dedicated IP option
DMARC monitoring
Partial
Add-on
Email validation

Use Cases

Transactional only
Marketing campaigns
Inbound email
Pro+
Free tier (no CC)

Deep Dive: DX, API & Deliverability

Best Developer Experience: Resend

Resend (founded 2023 by Zeno Rocha, former Vercel DevRel) is built for modern developers. Its standout feature is React Email — write email templates in JSX, preview in the browser, and ship with one API call. The REST API is clean, docs are beautiful, and the free tier gives you 100 emails/day with 1 domain and 1 webhook. Pro at $20/month gets you 50,000 emails, 10 domains, 10 webhooks, and 3-day retention. Scale ($90/mo) adds 100K emails, 1,000 domains, 7-day retention, and dedicated Slack support.

Resend
Best for: teams that value DX and React/Next.js

Best Deliverability & Speed: Postmark

Postmark (founded 2010, now part of ActiveCampaign) is known for the best deliverability in the industry — 99%+ to inbox — and average delivery in under 1 second. It's transactional email only (no marketing); that focus is a feature. Basic is $15/month for 10,000 emails with 45-day retention. Pro ($16.50) adds inbound email; Platform ($18) adds unlimited team and more streams. Dedicated IP is $50/month (300K+ emails). DMARC monitoring is a $14+/month add-on. Free Developer tier: 100 emails/month for testing, no credit card.

Postmark
Best for: critical transactional email (password resets, receipts, alerts)

Best for Scale & Enterprise: SendGrid

SendGrid (founded 2009, acquired by Twilio 2019) handles billions of emails and offers both marketing and transactional email. The free plan was retired May 27, 2025 — now only a 60-day free trial (100 emails/day). Essentials starts at $19.95/month (up to 100K emails); Pro from $89.95/month (up to 1.5M emails) includes dedicated IP and 2,500 email validations. Premier is custom. You get dynamic templates, advanced analytics, and enterprise-grade scale. Deliverability is good but reviews can be inconsistent; shared IP on lower tiers can affect reputation.

SendGrid
Best for: high volume, marketing + transactional, enterprise

Which Should You Choose?

Best DX & modern stack (React/Next.js)

Choose Resend. React Email, clean API, and great docs make it the best developer experience. Free tier (100 emails/day) is the most generous; Pro at $20/month for 50K emails is strong value for startups.

Resend
Recommended: Resend

Deliverability and speed are critical

Choose Postmark. 99%+ inbox rate and sub-second delivery are best-in-class. Transactional-only focus means no marketing bloat. Basic at $15/month for 10K emails is great value; 45-day retention is generous.

Postmark
Recommended: Postmark

High volume, marketing + transactional, enterprise

Choose SendGrid. Need both campaigns and transactional, or sending millions of emails? SendGrid is proven at scale. Note: free plan is gone (60-day trial only); Essentials starts at $19.95/month.

SendGrid
Recommended: SendGrid

Best value for early-stage startups

Resend Pro ($20/mo for 50K) or Postmark Basic ($15/mo for 10K). Resend wins if you send more volume and want React Email; Postmark wins if deliverability and retention matter more and 10K is enough.

Resend
or
Postmark
Resend or Postmark

Find the Perfect Stack for Your Business

Email is one piece of the puzzle. Use our tool catalog to explore email APIs, hosting, auth, databases, and more — and build a stack that fits your budget and team.

Frequently Asked Questions

What is the best free transactional email API in 2026?

Resend offers the best free tier: 100 emails per day (about 3,000/month), 1 domain, 1 webhook, no credit card required. Postmark has a Developer free tier (100 emails/month for testing). SendGrid retired its free plan in May 2025 and now only offers a 60-day trial.

Which has the best deliverability: Resend, SendGrid, or Postmark?

Postmark is widely regarded as having the best deliverability in the industry, with 99%+ inbox rates and average delivery in under 1 second. Resend and SendGrid both have good deliverability; SendGrid's can vary on shared IP tiers. For critical transactional email (password resets, receipts), Postmark is the safest choice.

Can I use Postmark or Resend for marketing emails?

Postmark is transactional email only — no marketing campaigns. Resend is focused on transactional email as well. For marketing (newsletters, campaigns), use SendGrid or a dedicated tool like Mailchimp, ConvertKit, or Loops.

What is React Email and why does Resend use it?

React Email lets you build email templates using JSX/React components. You get a component-based workflow, live preview in the browser, and type safety. Resend integrates natively with React Email, making it the best choice for React and Next.js developers who want to code emails like UI.

Does SendGrid still have a free plan?

No. SendGrid retired its free plan on May 27, 2025. New users get a 60-day free trial with 100 emails per day. After that, you need a paid plan (Essentials starts at $19.95/month).

Resend vs Postmark for a SaaS startup — which to pick?

If you value developer experience and use React/Next.js, choose Resend (React Email, great docs, $20/mo for 50K). If deliverability and speed matter most (e.g. login links, receipts), choose Postmark ($15/mo for 10K, 99%+ inbox, <1s delivery). Many startups start with Resend for DX and only switch to Postmark if they hit deliverability issues.

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