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Head-to-head · Email APIs

Postmark vs OpenSend

  • Updated Oct 2026
  • Both researched from official sources
  • 8 checks side by side
Higher score Postmark #5 in Email APIs 8.8/10 Free plan Free plan✓ 5 of 5 features Visit Postmark
OpenSend #19 in Email APIs 6.8/10 Free plan Free plan✓ 4 of 5 features Visit OpenSend

Postmark leads on 1 check, OpenSend on 2, and 5 are even. Who comes out ahead on the 8 yes/no, price and count checks where we have data for both products. The editor score weighs everything else too.

Our verdict

  • Highest scorePostmark · 8.8/10
  • Lowest starting priceOpenSend · $10/mo
  • Free planboth
  • Most featuresPostmark · 5 of 5

Postmark scores higher on our rubric for email apis: 8.8 against 6.8 out of 10; our editors rank them #5 and #19.

OpenSend is cheaper to start at $10/mo against $15/mo. OpenSend leads on monthly send limit: 15000 /mo versus 10000 /mo. Postmark offers smtp relay; OpenSend doesn't.

Postmark is the better fit for transactional email teams prioritizing deliverability. OpenSend is the better fit for open-source teams wanting a modern email stack.

  • Postmark fits best

    Transactional email teams prioritizing deliverability

  • OpenSend fits best

    Open-source teams wanting a modern email stack

Advertiser disclosure: iTechGuides is reader-supported. Vendors can pay for top positions in our rankings and for a place on other products' pages, and we may earn a commission when you click some links. Bought places stand at the number bought; this page and our disclosure say so. Paying vendors may get a fuller, more detailed review from our editors, and that review can change their score. How we rank.

Side by side

Feature Postmark 8.8/10 Visit ↗ OpenSend 6.8/10 Visit ↗
At a glance
Editor score 8.8 6.8
Ranking #5 in Email APIs #19 in Email APIs
Best for Transactional email teams prioritizing deliverability Open-source teams wanting a modern email stack
Pricing model Free plan + paid Free plan + paid
Starting price $15/mo $10/mo (best)
Free plan ✓ ✓
Free trial — —
Deployment Cloud Cloud, Self-hosted
Platforms Web Web
Integrations 12 integrations 8 integrations
Features Postmark 5/5 · OpenSend 4/5
Inbound email ✓ ✓
Delivery event webhooks ✓ ✓
SMTP relay ✓ (best) —
Email templates ✓ ✓
Dedicated IP option ✓ ✓
Specs
Monthly send limit 10000 /mo 15000 /mo (best)
Our review
Pros
  • REST API, SMTP sending, and separate transactional and broadcast streams
  • Delivery, bounce, open, click, and spam complaint webhooks
  • Inbound email parsing, templates, analytics, and official libraries
  • Self-hosting with Docker Compose, AWS SES, and Postgres
  • Resend-compatible REST API with TypeScript SDK and React Email support
  • Webhooks, inbound routes, automations, templates, and domain authentication
Cons
  • Free plan allows only 100 emails per month
  • Basic and Pro plans limit monthly volume to 10,000 emails
  • Broadcast and transactional workflows require stream management
  • SMTP relay is not supplied
  • Self-hosting requires AWS SES and Postgres
  • The Free plan allows 500 API and broadcast emails monthly
Our verdict

Postmark is an email delivery service for application teams sending transactional and broadcast messages through REST APIs or SMTP. It supports individual and batch messages, separate message streams, reusable HTML and plain-text…

Read the review →

OpenSend is email infrastructure for developers and teams managing transactional email, broadcasts, contacts, templates, automations, inbound messages, and delivery events. It supports web access, an API, and self-hosted deployment. Its…

Read the review →
  1. PostmarkEmail APIs 8.8Free plan
  2. OpenSendEmail APIs 6.8Free plan

Strengths and trade-offs

  • Postmark — where it wins

    • REST API, SMTP sending, and separate transactional and broadcast streams
    • Delivery, bounce, open, click, and spam complaint webhooks
    • Inbound email parsing, templates, analytics, and official libraries

    Where it doesn't

    • Free plan allows only 100 emails per month
    • Basic and Pro plans limit monthly volume to 10,000 emails
    • Broadcast and transactional workflows require stream management

  • OpenSend — where it wins

    • Self-hosting with Docker Compose, AWS SES, and Postgres
    • Resend-compatible REST API with TypeScript SDK and React Email support
    • Webhooks, inbound routes, automations, templates, and domain authentication

    Where it doesn't

    • SMTP relay is not supplied
    • Self-hosting requires AWS SES and Postgres
    • The Free plan allows 500 API and broadcast emails monthly

More comparisons

All email APIs comparisons → · Full ranking →

Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026

Last updated · How we research and update