For developers

Embed our editor in 5 lines .

Your SaaS users want a better email editor. We ship JWT auth, RLS multi-tenancy, and an MCP server out of the box. Wire it up and ship.

Get an API key Read the docs

Free Developer tier covers sandbox and staging. No credit card.

EmailEditor.tsx TSX

import { PosternEditor } from '@postern/react';

export default function EmailEditor() {
  return (
    <PosternEditor
      tenantId="cust_123"
      jwtToken={generateJWT()}
      onSave={(template) => sendToYourAPI(template)}
    />
  );
}

Multi-tenant, authenticated, ready for production. Substitute generateJWT() with your existing auth.

We built the hard parts so you don’t have to.

Email editors look easy until you start one. Rendering across Outlook, Gmail iOS, and Apple Mail. Versioning. Brand-safe sanitisation. Audit trails for compliance review. Tenant isolation that survives a misplaced WHERE clause.

We spent three months on architecture before we shipped the first block. Your team can spend that time on features your users will actually thank you for.

Plus the things you don’t want to staff: AI generation, tablet support, five-language UI on day one. Building those yourself is a 6-to-9 month project. Embedding ours is a week.

Built for SaaS, by people who ship SaaS

Three pieces that earn the integration cost.

RLS out of the box.

PostgreSQL Row-Level Security on every tenant-scoped table. Every request sets `app.current_tenant_id` via middleware. If we forget a WHERE clause, the database refuses anyway.

JWT or API key. Your call.

Mint an RS256 widget token in your app, pass it to the editor. Five-minute lifetime, no session glue. Server-to-server traffic uses Sanctum API keys with scopes.

MCP server included.

Pair with Claude, n8n, Zapier. Auto-generate subject lines, run tone checks, pull merge tags from your CRM. The agentic workflows your customers want, without you wiring them yourself.

Three embed modes

Match your stack.

The React SDK is the smoothest. The iframe is the fastest to ship. The Web Component is the framework-agnostic answer. Same JWT, same callbacks across all three.

React SDK

@postern/react. Full TypeScript types. Streamed AI responses. Forwards your existing auth.

EmailEditor.tsx TSX

import { PosternEditor } from '@postern/react';

export default function EmailEditor() {
  return (
    <PosternEditor
      tenantId="cust_123"
      jwtToken={generateJWT()}
      onSave={(template) => sendToYourAPI(template)}
    />
  );
}

iframe

One-line embed for Vue, Rails, anything that can render markup. PostMessage relay for save callbacks.

layout.html HTML

<iframe
  src={`https://embed.postern.io/editor?token=${jwt}`}
  allow="clipboard-write"
  width="100%"
  height="640"
></iframe>

Web Component

Custom element. Works in any host that respects HTML. Tree-shaken to ~120 KB gzipped.

page.html HTML

<script
  type="module"
  src="https://embed.postern.io/widget.js"
></script>

<postern-editor
  tenant-id="cust_123"
  jwt-token="<your-jwt>"
></postern-editor>

SDK packages are scheduled for v0.1.0 — Free Developer signups receive early access notes and the npm tarball before the public release.

Real integrations, sixty seconds each

Where this lands.

CRM with email

Your CRM has an email feature; users complain it’s clunky. Embed Postern. Support tickets drop. Users stay inside your app instead of jumping to Mailchimp.

E-commerce platform

Shopify-like merchants send five campaigns a year because the editor is painful. White-label Postern. Cadence rises to weekly without you adding headcount.

Automation platform

You’re a Make or n8n. Users automate workflows; the email step is the weak link. Embed Postern. Compose with AI, send to five ESPs, charge an extra $50 / mo per seat.

Surface area

Everything you need to integrate.

React SDK Drop-in component, full TypeScript types, peer-dep on React 18+
Web Component For Vue / Angular / Svelte / vanilla JS — same JWT, same callbacks
REST API /v1/templates, /v1/widget-tokens, /v1/render — RFC 7807 error responses
Webhooks template.saved, ai.generated, render.completed — signed with HMAC-SHA-256
MCP server Postern exposes tools via MCP — Claude Desktop reads it natively
Examples GitHub repo with starters: Next.js, Remix, Vue, Angular, vanilla TS

Built for serious teams

The compliance + reliability story.

SOC 2 Type II

Audit underway, target Q3 2026. Type I report available under NDA today.

EU + US data residency

Pick your region at provisioning. EU lives in eu-west-1, US in us-east-1. No cross-region replication unless you ask.

Multi-LLM provider

Anthropic primary, AWS Bedrock fallback. Bring-your-own-key for enterprise. Routing is configurable per tenant — you’re not locked to one model vendor.

Open API contract

OpenAPI 3.1 spec is the source of truth. SDKs are generated from it. The JSON Schema for templates is also published.

Pricing for developers

Designed for startups and scale-ups.

Free Developer covers sandbox and staging at zero cost. Production starts at $149 / mo with 10K seats. Full breakdown on the pricing page.

Free Developer$0 — non-prod
Startup$149 / mo — 10K seats
Growth$349 / mo — 100K seats
EnterpriseFrom $1,500 / mo — SLA

Wire it up in an hour. Ship in a day.

Free Developer tier. Full API surface. Slack channel for direct questions while you integrate. We answer in business hours, US-East and EU-West.

Get an API key Book an engineering demo