The Best Postmark Alternative for Transactional Emails
Compare Keplars and Postmark across APIs, SMTP, templates, analytics, automations and email infrastructure. Built for startups, SaaS products and growing teams.
Why Teams Look For a Postmark Alternative
Postmark has a strong reputation for transactional deliverability and clean API design. As teams grow, they often need capabilities that Postmark does not offer: OAuth sending to avoid DNS setup, marketing campaigns, AI-powered templates, mailbox warmup, and a much more accessible free tier to get started without a credit card.
- No DNS Setup Required
Postmark requires DKIM and Return-Path DNS records before you can send a single email. Keplars lets you authenticate via Gmail, Google Workspace, or Outlook through OAuth and start sending instantly with no DNS configuration.
- Transactional and Marketing Together
Postmark is focused exclusively on transactional delivery. Keplars handles both transactional emails and marketing campaigns from the same platform. No need to run separate tools when you want to reach your users.
- Dramatically Better Pricing
Postmark's free tier is limited to 100 emails per month, with paid plans starting at $15/mo for 10,000 emails. Keplars gives you 5,000 emails free every month and paid plans starting at just $5/mo.
Postmark vs Keplars Feature Comparison
A side-by-side look at features, infrastructure, developer tools, and pricing.
| Feature | Keplars | Postmark |
|---|---|---|
| Email API | REST API with simple HTTP calls | REST API |
| SMTP | Port 587, STARTTLS, drop-in replacement | Available |
| OAuth Email Sending | Gmail, Google Workspace, Outlook | Not supported |
| No DNS Setup Required | Start sending via OAuth in minutes | DKIM and Return-Path DNS records required for all accounts |
| SDKs | 11 languages | 8 official + 20+ community libraries |
| CLI | Full developer CLI | Official CLI available |
| Unified Email Editor | Drag & drop + code editor in one tool | Code-based HTML templates only, no visual builder |
| Canva / Figma Import | Import designs and send directly | No direct design import supported |
| Real-time Email Tracking | Open time, delivered time, click time per email | Opens, clicks, delivery with timestamps and geolocation |
| Webhooks | All lifecycle events, included | Bounces, spam, delivery, opens, clicks |
| Automations | Included with AI-generated templates | Via third-party integrations only |
| Marketing Campaigns | Campaigns and lifecycle flows, included | Transactional only. Marketing requires third-party tools |
| Mailbox Warmup | Included | Not available |
| Sandbox Mode | Full sandbox. No impact on daily limit | Sandbox server for safe testing |
| Analytics | Real-time dashboard, all plans | Opens, clicks, delivery with geolocation and client data |
| Domain Authentication | Auto-managed SPF, DKIM, DMARC | Manual DNS setup required |
| Integrations | Vercel, Firebase, Supabase, Lovable, n8n, Zapier, Bubble, Payload CMS, PocketBase, React Email, and more | Datadog, Stripe, Slack, Zapier, Customer.io, Supabase, Bubble, and more |
| Marketing Email Pricing | Usage-based. Pay per email sent, not contacts stored | Volume-based for transactional. No native marketing product |
| Free Plan | 5,000 emails/mo | 100 emails/mo only |
| Paid Plan Starts At | $5/mo | $15/mo for 10,000 emails |
| Support | Responsive, all plans | Email support available |
Why Developers Choose Keplars Over Postmark
- OAuth Email Sending
Send from Gmail, Google Workspace, or Outlook via OAuth. Your real inbox reputation powers every email with zero DNS setup.
- AI-Generated Templates
Generate polished, responsive email templates with AI. No designer or HTML expertise required.
- Visual Email Editor
Drag-and-drop and code editing in one unified tool. Postmark offers a code-only template engine with no visual builder.
- Canva and Figma Import
Import designs from Canva or Figma directly into the Keplars editor and send them as emails without reformatting.
- Marketing Campaigns
Run broadcast campaigns and lifecycle flows alongside your product emails. Postmark has no native marketing product.
- Mailbox Warmup
Automatically warm up new sending domains and mailboxes to build reputation before going full volume. Not available in Postmark.
- Wider Integration Ecosystem
Integrates natively with Vercel, Firebase, Supabase, Lovable, n8n, Zapier, Bubble, Payload CMS, PocketBase, React Email, and Dodo Payments.
- Better Free Tier
5,000 emails per month on the free plan versus Postmark's 100. Far more headroom to build and test before you ever pay.
Built for Modern SaaS Applications
Every email type your product needs, handled from one platform.
Welcome emails and account setup sequences delivered reliably from day one.
Secure, branded password reset links delivered instantly to your users.
One-time password codes that arrive in under 5 seconds, every time.
Email address confirmation flows that complete fast and land in the inbox.
Passwordless login links sent and received in seconds for frictionless auth.
Invoices and receipts as HTML or PDF delivered straight to customer inboxes.
Trial expiry, renewal reminders, and subscription change confirmations.
Broadcast campaigns and drip sequences sent from the same platform as your product emails.
Email Infrastructure Beyond Transactional Emails
Postmark is a transactional email delivery service. Keplars is a complete email platform. Manage everything from a single dashboard.
- Transactional Emails
APIs and SMTP for OTPs, resets, invoices, and all product-critical email.
- Marketing Emails
Broadcast campaigns and lifecycle email flows from the same platform.
- Templates
AI-generated, drag-and-drop, and code editor. All in one unified interface.
- Automations
Trigger-based email workflows with branching logic and delay controls.
- Real-Time Tracking
Open time, delivered time, click time, and full event timelines per email.
- Domains and Analytics
Manage sending domains, SPF, DKIM, DMARC, and a live analytics dashboard in one place.
How to Migrate From Postmark to Keplars
The core API concepts are similar. Most migrations take under 30 minutes.
Sign up at dash.keplars.com and create a new project. Takes under a minute.
Authenticate via OAuth with Gmail or Google Workspace, or add your custom domain with auto-managed DNS records.
Swap out postmark.ServerClient for the Keplars SDK and update your API key. Method names and field names differ slightly.
Copy your existing HTML templates or rebuild them with the AI-powered Keplars editor and visual designer.
Remap Postmark PascalCase event names (Delivery, Bounce) to Keplars dot-notation events (email.delivered, email.bounced).
Before vs After
const postmark = require("postmark");
const client = new postmark.ServerClient(
process.env.POSTMARK_SERVER_TOKEN
);
await client.sendEmail({
From: "[email protected]",
To: "[email protected]",
Subject: "Welcome!",
HtmlBody: "<h1>Welcome aboard</h1>",
MessageStream: "outbound",
});import { Keplars } from '@keplars/sdk';
const keplars = new Keplars({
apiKey: process.env.KEPLARS_API_KEY,
});
await keplars.emails.sendInstant({
to: ['[email protected]'],
subject: 'Welcome!',
html: '<h1>Welcome aboard</h1>',
is_html: true,
});Webhook event name mapping
Postmark uses PascalCase event names. Keplars uses lowercase dot-notation. Update your webhook handler event checks accordingly.
Templates, contact lists, and domain settings all carry over. Full details in the migration guide.
Why Startups Choose Keplars
- Scalable Infrastructure
Built to grow with your product. Start free, scale to millions of emails without re-architecting your email stack.
- Developer Experience First
Clean REST APIs, clear documentation, a developer CLI, and predictable behavior that feels natural in real production workflows.
- Transactional and Marketing Together
Stop running separate tools for product emails and marketing campaigns. Keplars handles both from a single dashboard.
- Analytics That Actually Help
Real-time open rates, click rates, delivery timelines, and bounce tracking. Know what happened to every email you sent.
- Automations Without Extra Cost
Trigger-based email workflows, drip sequences, and re-engagement flows are included. No additional tool or tier required.
- One Platform for Everything
APIs, SMTP, webhooks, templates, automations, tracking, domains, and analytics in one place. No tool sprawl.
Frequently Asked Questions
Ready to switch from Postmark?
Disclaimer: Comparisons are provided for informational purposes only and are based on publicly available data at the time of publication.
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