Senlo — Open-Source Email Editor & Infrastructure

Senlo is an open-source, self-hosted email editor and infrastructure for product, transactional, and lifecycle emails.

It provides a visual builder, template management, contacts, and automation flows, while remaining provider-agnostic for email delivery.
You can integrate your own SMTP or ESP and keep full control over your data and workflows.

What Senlo Is For

• Transactional emails (password reset, receipts, verification)
• Product and lifecycle emails
• Embedded email editors inside SaaS products
• Teams that want self-hosted or white-label solutions

Core Capabilities

• Visual drag-and-drop email editor
• Template versioning and structured JSON documents
• Dynamic variables and preview with mock data
• Provider-agnostic integrations (SMTP / ESP APIs)
• Multi-project and multi-user isolation
• Self-hosted deployment

Senlo gives you the engine and UI.
You decide how emails are stored, rendered, and sent.

Why Senlo

Most email platforms combine editing, sending, analytics, and marketing tools into a single closed ecosystem.
Senlo separates concerns and provides an open infrastructure layer that you can integrate into your own stack.

This makes it suitable for:

• SaaS products that need built-in email editing
• Agencies requiring white-label solutions
• Teams that want to avoid vendor lock-in
• Developer-first workflows

Architecture

apps/
  web/                  # Next.js Application (The Dashboard & API)

packages/
  core/                 # Domain models, MJML/HTML renderers, interfaces
  editor/               # The visual builder engine
  ui/                   # Reusable UI component library (design system)
  db/                   # Database schema, migrations, and repositories

Technology Stack

• Frontend: Next.js 16 (App Router), React 19, Tailwind CSS.
• State Management: Zustand (Immer for state immutability).
• Backend: Next.js Server Actions & API Routes.
• Database: PostgreSQL with Drizzle ORM.
• Communication: Auth.js, Zod (Validation), Resend/Mailgun (Sending).
• Package Management: pnpm workspaces (Monorepo).

Author

Igor Filippov

• GitHub: @IgorFilippov3

Quick Start

Local Development

1. Install dependencies:

   pnpm install

2. Setup your environment: Copy .env.example to apps/web/.env and fill in your database URL and secret.
3. Push the schema:

   pnpm db:push

4. Start the dev server:

   pnpm dev

Production Deployment (Self-hosted)

The easiest way to deploy Senlo is using Docker Compose. Check our VPS Deployment Guide for step-by-step instructions.

Status

Senlo is currently in active development (MVP stage). We are stabilizing the API and adding core features. Contributions and feedback are welcome!

Check out our Roadmap for planned features and upcoming improvements.