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Open Source Email & Communication Tools

A curated collection of the best open source tools related to email and other communication methods..

See also:Secure Email ProvidersPush NotificationEmail ClientsMail ServersEmail Platforms

Novu

Multi-channel notification infrastructure for apps

  • Stars

    40,197

  • Last commit

    16 hours ago

  • License

    Unknown
Open-source platform for building in-app, email, push, SMS, and chat notifications with a unified API, workflow engine, and embeddable inbox component.

Open Source Alternative to:

Customer.io

Macro Mail

Keyboard-first email client with AI, chat, and tasks

  • Stars

    Stars growing quickly over the last 30 days4,898

  • Last commit

    2 hours ago

  • License

    AGPL-3.0
An AI-powered email client that combines inbox management, chat, tasks, and AI agents in one shared workspace, built for keyboard-driven workflows.

Open Source Alternative to:

Gmail

Ntfy

Simple, fast, and secure push notifications for all

  • Stars

    35,035

  • Last commit

    2 hours ago

  • License

    Apache-2.0
A lightweight, open-source solution for sending real-time notifications to your devices, with end-to-end encryption and no sign-up required.

Open Source Alternative to:

LogSnag

Billion Mail

AI
Open-source mail server with unlimited sending & AI tools

  • Stars

    15,951

  • Last commit

    5 months ago

  • License

    AGPL-3.0
Self-hosted email marketing platform with unlimited sending, AI-powered email creation, real-time analytics, and no monthly fees. Complete SMTP solution.

Open Source Alternative to:

Resend

Mailspring

Native desktop email with tracking, templates, and dark mode

  • Stars

    17,938

  • Last commit

    1 day ago

  • License

    GPL-3.0
Desktop email client for Mac, Windows, and Linux with unified inbox, read receipts, link tracking, send later, grammar checking, and contact enrichment.

Open Source Alternative to:

Apple Mail

Postal

Self-hosted mail delivery platform for sending and receiving email

  • Stars

    16,890

  • Last commit

    4 days ago

  • License

    MIT
Run your own mail delivery infrastructure with a web interface, webhooks, IP pools, and spam filtering integrations for inbound and outbound email.

Open Source Alternative to:

Resend

Inbox Zero

AI email assistant that automates, organizes, and declutters

  • Stars

    Stars growing over the last 30 days12,794

  • Last commit

    1 day ago

  • License

    AGPL-3.0
Automates Gmail and Outlook with AI-drafted replies, bulk unsubscribe, cold email blocking, attachment filing, and inbox analytics for individuals and teams.

Open Source Alternative to:

Superhuman Mail

Thunderbird for Android

Privacy-first email app for Android, no ads ever

  • Stars

    14,136

  • Last commit

    2 days ago

  • License

    Apache-2.0
Android email client from the Thunderbird project with unified inbox, multiple account support, OpenPGP encryption, and no ads or data tracking.

Open Source Alternative to:

Gmail

Tuta

Secure email, calendar and contacts with end-to-end encryption

  • Stars

    8,043

  • Last commit

    8 hours ago

  • License

    GPL-3.0
Tuta offers encrypted email, calendar and contacts with quantum-resistant security, protecting your privacy without ads or tracking.

Open Source Alternative to:

Gmail

Roundcube

Browser-based IMAP webmail with a full email client feel

  • Stars

    7,242

  • Last commit

    2 days ago

  • License

    GPL-3.0
PHP-based webmail client with MIME support, address book, folder management, threaded views, PGP encryption, and a plugin API for self-hosted email.

Open Source Alternative to:

Gmail

Plunk

The open-source, affordable email platform

  • Stars

    5,540

  • Last commit

    2 hours ago

  • License

    AGPL-3.0
Plunk unifies marketing, transactional, and broadcast emails into a single, complete solution for businesses of all sizes.

Open Source Alternative to:

Resend

useSend

Pay per email sent, not for contact storage

  • Stars

    4,756

  • Last commit

    6 days ago

  • License

    AGPL-3.0
Open source email platform for transactional and marketing emails. Self-host or use cloud service with transparent pricing - pay only for emails sent.

Open Source Alternative to:

Resend

UnInbox

Transform team email into efficient collaborative workflows

  • Stars

    1,760

  • Last commit

    9 months ago

  • License

    AGPL-3.0
Streamline team communication with shared inboxes, unlimited email addresses, and customizable workflows. Perfect for modern businesses seeking organized email management.

Open Source Alternative to:

Gmail

Sessy

Own your SES email analytics, from send to inbox

  • Stars

    943

  • Last commit

    2 days ago

  • License

    Unknown
Track SES deliveries, bounces, opens and clicks in a self-hosted dashboard with real-time search, analytics and reputation monitoring.

Open Source Alternative to:

Resend

Hyvor Relay

Open-source email API with enterprise deliverability

  • Stars

    918

  • Last commit

    3 days ago

  • License

    AGPL-3.0
Self-hosted email API alternative to AWS SES & Mailgun. Open-source AGPL-3.0 with enterprise features, automated deliverability, and cloud version coming 2026.

Open Source Alternative to:

Resend

Twake Mail

Secure open source email with advanced encryption & AI

  • Stars

    660

  • Last commit

    1 day ago

  • License

    AGPL-3.0
Open source professional email solution with PGP encryption, JMAP protocol, AI-powered responses, and advanced antispam protection. Control your data privately.

Open Source Alternative to:

Gmail

Wraps

Code-first email platform that deploys to your AWS

  • Stars

    64

  • Last commit

    16 hours ago

  • License

    AGPL-3.0
Build email templates as React components and automations in TypeScript. Deploy to your AWS account with SES integration. Marketing teams edit content without code.

Open Source Alternative to:

Resend
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