Open-source email infrastructure for developers.
Transactional and marketing email through a REST API, SMTP relay and SDKs managed on bytesend.cloud or self-hosted on your own AWS account.

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Send your first email

import { ByteSend } from "bytesend-js";

const bytesend = new ByteSend("bs_your_api_key");

await bytesend.emails.send({
  from: "Acme <hello@acme.com>",
  to: "customer@example.com",
  subject: "Welcome to Acme",
  html: "<p>Thanks for signing up!</p>",
});

Prefer another language or no code at all? Use the Python or Go SDK, call the REST API directly, or point any app at the SMTP relay.

What's included

Sending

• REST API, SMTP relay, and SDKs for TypeScript, Python and Go
• Scheduled sends, batch sends of up to 100 emails, idempotency keys and custom headers
• Templates built in a visual editor, with variables
• Per-domain open and click tracking

Marketing

• Contact books with double opt-in and one-click (RFC 8058) unsubscribe
• Campaigns with batching and send windows

Deliverability

• Guided domain setup with DKIM, SPF (custom MAIL FROM) and DMARC checks
• Automatic suppression of hard bounces and complaints
• Bounce and complaint rates enforced per team at Google and Yahoo sender thresholds
• Outbound spam scoring: suspicious mail is flagged, high-risk mail is held for review
• Daily domain blocklist monitoring (Spamhaus DBL, SURBL, URIBL)
• Move a domain between SES regions without downtime

Operations

• Signed webhooks with retries for every email and domain event
• Team notifications to Discord, Slack, Microsoft Teams, Telegram or any webhook
• Teams with roles, API keys scoped by permission and domain, and 2FA
• An admin panel with platform overview, audit log, email explorer and spam review

Cloud or self-hosted

Cloud — bytesend.cloud is the fastest start: sign up, verify a domain and send. No infrastructure to run.

Self-hosted — ByteSend is free to self-host under AGPL-3.0. You bring PostgreSQL, Redis and an AWS account with SES.

git clone https://github.com/NodeByteLTD/ByteSend.git
cd ByteSend
cp docker/prod/.env.example docker/prod/.env   # fill in your values
docker compose -f docker/prod/compose.yml --env-file docker/prod/.env up -d
docker compose -f docker/prod/compose.yml --env-file docker/prod/.env exec web pnpm db:migrate-deploy

The self-hosting guide covers SES setup, reverse proxy and TLS, the SMTP relay and upgrades.

Local development

You need Node.js 20.19+, pnpm 9+ and Docker.

pnpm install
cp .env.example .env     # fill in values
pnpm dx:up               # Postgres, Redis and MinIO in Docker
pnpm db:migrate-dev      # apply database migrations
pnpm dev                 # web app on http://localhost:3000

Command	What it does
pnpm dev	Run every app in watch mode
pnpm build	Production build
pnpm lint	Lint all packages
pnpm test:web	Web unit tests (Vitest)
pnpm test:web:all	Unit and integration tests (needs pnpm dx:up)
pnpm db:studio	Open Prisma Studio
pnpm dx:down	Stop the local Docker services

The local setup guide walks through the environment variables.

Repository layout

Path	What's there
apps/web	Next.js dashboard, tRPC API, public REST API (Hono) and background jobs
apps/smtp-server	SMTP relay that forwards mail to the ByteSend API
apps/docs	Documentation site
packages/sdk	TypeScript SDK (bytesend-js)
packages/python-sdk	Python SDK (bytesend)
packages/go-sdk	Go SDK (github.com/nodebyteltd/bytesend-go)
packages/ui	Shared UI components
packages/email-editor	Visual email template editor

Built with Next.js 16 · TypeScript · tRPC · Hono · Prisma · PostgreSQL · Redis · BullMQ · AWS SES · NextAuth · Tailwind CSS · Turborepo

Contributing

Contributions are welcome.

1. Open or comment on an issue first, so work doesn't overlap.
2. Branch from develop and use Conventional Commits (feat(scope): …, fix(scope): …).
3. Open your pull request against develop.

Read the contributing guide and code of conduct before you start. Notes for AI coding agents are in AGENTS.md.

Found a security issue? Please report it privately as described in the security policy rather than opening an issue. For help, see support.

License

ByteSend is licensed under the GNU Affero General Public License v3.0. If you run a modified version as a network service, the AGPL requires you to make your changes available to its users.