Flagsmith vs Postmark
Open-source feature flags + remote config — SaaS, private cloud, self-host
vs. Reliable transactional email with fast delivery
Pricing tiers
Flagsmith
Free
$0. 50,000 API requests/mo. 1 team member. Unlimited flags. Community support.
Free
Self-hosted
$0 (OSS). Host yourself via Docker/K8s. Fair-source license (non-compete).
$0 base (usage-based)
Start-up
$40/mo. 1,000,000 API requests/mo. 3 team members. Standard support.
$40/mo
Scale-up
$200/mo. 5,000,000 API requests. 10 team members. Priority support + SLA.
$200/mo
Enterprise
Custom. Unlimited API requests, SSO, SAML, RBAC, audit logs, on-prem.
Custom
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
Free-tier quotas head-to-head
Comparing free on Flagsmith vs free on Postmark.
| Metric | Flagsmith | Postmark |
|---|---|---|
| No overlapping quota metrics for these tiers. | ||
Features
Flagsmith · 14 features
- A/B Testing — Multivariate flag splits.
- Audit Log — Full history of flag changes.
- Change Requests — Approval workflow for flag changes.
- Edge API — Global low-latency flag eval.
- Feature Flags — Boolean + multivariate + JSON flags.
- Local Evaluation — Server SDKs eval flags locally — no per-req API call.
- Percentage Rollouts — Gradual traffic ramp.
- Remote Config — Non-boolean config values.
- Role-Based Access — Fine-grained permissions.
- Scheduled Flags — Time-based flag changes.
- Segments — Rule-based targeting.
- Self-Hosting — Docker/Helm install.
- SSO + SAML — Enterprise SSO.
- Webhooks — Outbound event streaming.
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.
Developer interfaces
| Kind | Flagsmith | Postmark |
|---|---|---|
| CLI | Flagsmith CLI | — |
| SDK | flagsmith-android, flagsmith-go, flagsmith-ios, flagsmith-java, flagsmith-js (browser), flagsmith-nodejs, flagsmith-python, flagsmith-ruby | postmark-dotnet, postmarker (Python), postmark-go, postmark (Node), postmark-php, postmark-rails |
| REST | Flagsmith REST API | Postmark REST API |
| OTHER | Flagsmith Dashboard, Flagsmith Webhooks | Inbound Email, SMTP Relay, Webhooks |
Staxly is an independent catalog of developer platforms. Outbound links to Flagsmith and Postmark are plain references to their official websites. Pricing is verified against vendor pages at publication time — reconfirm before buying.
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