Postmark vs Clerk
Reliable transactional email with fast delivery
vs. User management and authentication as a service
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
Clerk
Free
50k MAU included. No SSO/SAML. Perfect for side projects and early prototypes.
Free
Pro
$25/mo (or $20/mo annual). 50k MAU, $0.02 each after. 1 enterprise SSO connection per app. Webhooks, JWT templates, custom session duration.
$25/mo
Business
$300/mo (or $250/mo annual). Advanced organizations, enhanced support, additional enterprise features.
$300/mo
Enterprise
Custom. Volume MAU discounts, SLA, workspace-wide SAML SSO, dedicated support.
Custom
Free-tier quotas head-to-head
Comparing free on Postmark vs hobby on Clerk.
| Metric | Postmark | Clerk |
|---|---|---|
| mao | — | 100 orgs/month |
| mau | — | 50000 users/month |
| sso connections | — | 0 connections |
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.
Clerk · 15 features
- Account Portal — Hosted sign-in/user profile pages at accounts.yourapp.com — zero UI code, fully …
- Bot Protection — Cloudflare Turnstile CAPTCHA integrated into sign-up.
- Clerk Billing — Built-in Stripe-powered billing: subscriptions, plans, proration — ties directly…
- Enterprise SSO (SAML/OIDC) — SAML and OIDC for enterprise customers. Per-domain connection. Pro+ (1 included)…
- Impersonation — Act as a user from dashboard to debug. Logged.
- JWT Templates — Custom JWT issuance for third-party backends (Supabase, Hasura, Firebase, Convex…
- Machine Tokens (M2M) — API keys and machine tokens for service-to-service auth in addition to user sess…
- Multi-Factor Auth — TOTP (authenticator apps), SMS OTP, backup codes. Forced or optional per user.
- Organizations (B2B) — Multi-tenant orgs with roles, permissions, invitations, domain allowlist, and pe…
- Passkeys (WebAuthn) — Passwordless passkey sign-in with per-device biometrics.
- Prebuilt Components — Drop-in React components: <SignIn/>, <SignUp/>, <UserButton/>, <OrganizationSwit…
- Sessions — Server-side session tokens. Sliding expiration by default; configurable absolute…
- User Management — Full user CRUD, metadata (public/private/unsafe), email/phone verification, ban/…
- Waitlist Mode — Collect sign-ups before opening the app. Approve waitlist entries to activate ac…
- Webhooks — Events: user.created/updated/deleted, session.created, organization.* — delivere…
Developer interfaces
| Kind | Postmark | Clerk |
|---|---|---|
| SDK | postmark-dotnet, postmarker (Python), postmark-go, postmark (Node), postmark-php, postmark-rails | @clerk/astro, @clerk/backend / @clerk/clerk-sdk-node, @clerk/chrome-extension, @clerk/clerk-expo, @clerk/clerk-js (vanilla), @clerk/clerk-react, @clerk/clerk-react-native, @clerk/nextjs, @clerk/nuxt, @clerk/remix, clerk-sdk-go, clerk-sdk-python, clerk-sdk-ruby, @clerk/tanstack-start, @clerk/vue |
| REST | Postmark REST API | Backend REST API, Frontend API |
| MCP | — | Clerk MCP |
| OTHER | Inbound Email, SMTP Relay, Webhooks | Webhooks (Svix) |
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