useSend is an open source email sending platform that replaces proprietary services like SendGrid and Resend by offering a self-hostable, transparent alternative built on Amazon SES. It’s designed for developers, startups, and teams who want full control over their email infrastructure without vendor lock-in or hidden costs. With real-time analytics, a WYSIWYG email editor, and SMTP relay, useSend eliminates the need for third-party email APIs while keeping costs low.
Built with Next.js, Prisma, and tRPC, useSend provides a modern web dashboard and supports multiple programming languages via typed SDKs. It can be deployed via Docker, Railway, or on-premises, and integrates with existing systems through REST API, SMTP, and webhooks. The platform is AGPLv3 licensed and actively developed by a community of open source contributors.
What You Get
- Visual Email Editor - A No-Code WYSIWYG editor powered by Tiptap and JSX-Email that lets users design marketing emails with templates, variables, and brand styles compatible with major email clients.
- Real-Time Email Analytics - Track deliveries, opens, clicks, bounces, and unsubscribes with searchable logs filtered by domain, API key, or campaign, with export functionality for reporting.
- SMTP Relay - Drop-in SMTP server that works with any application or framework (e.g., Supabase, WordPress) without requiring API integration, eliminating vendor lock-in.
- Contact & List Management - Manage subscriber lists, import/export contacts via CSV, and automatically sync subscription status from bounces and complaints.
- Suppression List - Automatically blocks emails to addresses that have bounced or complained, with manual import/export and API-based management for both transactional and marketing emails.
- Multi-Language SDKs - Official typed SDKs for TypeScript, Python, Go, and PHP with documented examples for sending emails programmatically in any stack.
- Scheduled Email API - Schedule email delivery for future times via API, enabling automated workflows like drip campaigns or event-triggered notifications.
- Webhook Support - Receive real-time event notifications (delivered, opened, clicked, bounced) via HTTP POST to your endpoint for custom integrations.
Common Use Cases
- Running a paid membership newsletter - A SaaS founder uses useSend to send weekly newsletters to 30k+ subscribers with open/click tracking, while avoiding SendGrid’s pricing tiers and maintaining full data ownership.
- Integrating email into a self-hosted app - A developer using Supabase adds useSend’s SMTP relay to send password resets and account notifications without relying on external email vendors.
- Building a marketing automation tool - A startup uses useSend’s visual editor and scheduled API to create and deploy personalized email campaigns with dynamic variables and A/B testing.
- Replacing a costly email service - A small business migrates from Resend to useSend to cut monthly costs by 80%, self-hosting the platform on Railway with full control over data and delivery logs.
Under The Hood
Architecture
- Monorepo structure with Turbo enables independent development of apps and shared packages, enforcing clear separation of concerns between UI, email composition, and SMTP delivery layers
- Domain-driven design isolates responsibilities: email-editor for rich-text, smtp-server for protocol logic, and web app for UI, with dependency injection via workspace references
- Prisma ORM provides centralized database schema management and consistent data modeling across services, while allowing app-specific query flexibility
- Event-driven patterns are implicitly supported through webhook endpoints and SMTP integration, facilitating asynchronous email delivery pipelines
Tech Stack
- TypeScript monorepo managed by pnpm and Turbo for efficient cross-package builds and caching
- Next.js 15 with React 19 and @mdx-js for dynamic marketing content, paired with Hono and tRPC for type-safe server-side APIs
- SMTP server built with nodemailer and smtp-server, complemented by mailparser for email parsing and analysis
- Comprehensive testing infrastructure using Vitest, Dockerized environments, and mocked external services for deterministic test execution
Code Quality
- Extensive test coverage across unit, integration, and middleware layers with clean dependency mocking and precise behavior assertions
- Strong type safety enforced through Prisma-generated types, explicit enums, and consistent interfaces that prevent runtime data errors
- Robust error handling with custom API error classes and standardized response structures ensuring predictable behavior across endpoints
- Clean separation of concerns via modular service layers, dedicated route handlers, and encapsulated middleware for auth and rate limiting
- Consistent naming, header sanitization, and environment isolation practices that enforce security and maintainability
What Makes It Unique
- Native multi-language SDKs with identical API semantics and auto-generated code examples create a seamless cross-platform developer experience
- Built-in rate limiting and waitlist validation using Redis eliminate reliance on external services while maintaining performance
- Unified email rendering engine supports both transactional and marketing emails with dynamic templating and automatic HTML escaping
- OpenAPI-first API design with Hono and zod-openapi enables automatic schema validation and documentation without manual contract upkeep
- Interactive, copyable code examples embedded directly in the UI transform documentation into an actionable product feature