Postmark vs Cal.com
Reliable transactional email with fast delivery
vs. Open-source scheduling infrastructure — the self-hostable Calendly alternative
Pricing tiers
Postmark
Free
100 emails/month forever. No credit card. Side projects and testing.
Free
Basic — 10k
10,000 emails/month. Overage $1.80/1k. Unlimited emails/day.
$15/mo
Pro — 10k
10,000 emails/month. Overage $1.30/1k. Inbound email + message streams.
$17/mo
Platform — 10k
10,000 emails/month. Overage $1.20/1k. Team collab, more domains.
$18/mo
Enterprise (>1.5M)
Custom for senders exceeding 1.5M/month.
Custom
Cal.com
Free (Cloud)
$0. 1 user. Unlimited event types. Unlimited meetings. Cal branding.
Free
Self-Hosted (OSS)
Free forever. AGPL-3.0. Docker/K8s deploy. Full feature parity with cloud.
$0 base (usage-based)
Teams
$12/user/mo. Round-robin, collective events, routing forms, Cal Video, Workflows.
$12/mo
Organizations
$37/user/mo. SSO, advanced routing, dashboards, analytics, dedicated support.
$37/mo
Enterprise
Custom. SAML, HIPAA, dedicated deployments, security reviews.
Custom
Free-tier quotas head-to-head
Comparing free on Postmark vs free on Cal.com.
| Metric | Postmark | Cal.com |
|---|---|---|
| No overlapping quota metrics for these tiers. | ||
Features
Postmark · 12 features
- Activity Search — Full-text search over sent messages for 45-365 days.
- Bounce Handling — Automatic hard/soft bounce detection + suppression management.
- Broadcast Messages — Via separate Broadcast Message Stream. Bulk sends with throttling.
- DKIM + SPF — One-click verification + auto-renewal of DKIM keys.
- Inbound Email — Route inbound emails to your webhook. Parse attachments, threads.
- Message Streams — Isolate transactional from marketing for separate deliverability reputation.
- Open + Click Tracking — Configurable at template or send level.
- Raw API Access — 100+ endpoints for bounces, servers, tags, templates, stats.
- Servers — Multi-tenant isolation: each "server" has its own API token + reputation.
- Templates — Mustachio template language with variables, alias + versioning.
- Transactional Send — Reliable API for password resets, receipts, notifications. Sub-10s delivery.
- Webhook Events — Delivery, bounce, spam complaint, open, click, subscription change.
Cal.com · 16 features
- Availability — Multiple schedules per user.
- Buffer Time — Padding between meetings.
- Cal Video — Built-in video conferencing.
- Embed — Inline/popup/floating-button embeds.
- Event Types — One-on-one, group, collective, round-robin.
- Insights Dashboard — Booking trends + team analytics.
- Paid Bookings — Stripe integration for paid appointments.
- Platform API — Embed scheduling in your SaaS.
- Recurring Events — Weekly/monthly recurring bookings.
- Round-Robin — Distribute bookings across team.
- Routing Forms — Route leads by answers.
- Self-Host — Deploy to your infra.
- SSO — SAML + OIDC.
- Timezone Detection — Auto-detect viewer timezone.
- Webhooks — Outbound events.
- Workflows — Automated email/SMS reminders.
Developer interfaces
| Kind | Postmark | Cal.com |
|---|---|---|
| CLI | — | cal CLI (self-host) |
| SDK | postmark-dotnet, postmarker (Python), postmark-go, postmark (Node), postmark-php, postmark-rails | @calcom/embed-react |
| REST | Postmark REST API | Cal.com REST API v2, Platform API (embed in SaaS) |
| OTHER | Inbound Email, SMTP Relay, Webhooks | Cal.com Dashboard, Cal.com Webhooks |
Staxly is an independent catalog of developer platforms. Some links to Postmark and Cal.com 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.
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