Open-source HEY alternatives

Inbox Zero is an AI assistant for email, built to cut the time people spend in their inbox. It organizes messages, pre-drafts replies in the user's tone and style, manages the calendar and files attachments. It can also be chatted with from Slack or Telegram, and it is positioned as an open-source alternative to Fyxer that is more customizable and secure.

Its feature set includes AI rules written in plain English, Reply Zero to track emails awaiting a response, a bulk unsubscriber and bulk archiver, a cold email blocker, email analytics and meeting briefs that pull context from email and calendar. Smart filing saves attachments to Google Drive or OneDrive, and the project topics point to Gmail integration.

The app is built with Next.js, Tailwind CSS, shadcn/ui, Prisma and PostgreSQL in a Turborepo monorepo, with Upstash used for supporting services. A hosted version runs at getinboxzero.com, and the repository includes instructions for self-hosting. Feature requests go through GitHub issues or Discord, and the license is specified in the repository.

Tuta, formerly known as Tutanota, is an email service built around security and privacy. It uses built-in end-to-end encryption to protect emails, contacts and calendar entries across devices, and it lets users communicate securely with other people regardless of what provider they use.

The open-source repository contains the client applications, which include a web client, an iOS app and a desktop client, along with separate calendar releases for mobile platforms. The code is written in TypeScript and JavaScript on top of the Mithril framework and is licensed under GPL-3.0. Build, translation and development instructions are provided in dedicated files, and the roadmap and feature requests are handled through Reddit and the vendor website.

Tuta is a hosted service operated by the vendor rather than a product you install on your own server. The repository states that it does not accept contributions or bug reports produced with the help of large language models, and maintainers close such submissions without explanation.

Forward Email is an open-source email service focused on privacy. It handles custom-domain email forwarding and also provides mailboxes accessible over IMAP, POP and SMTP, with encryption using algorithms such as AES-256 and ChaCha20, and it positions itself as an all-in-one alternative to Gmail, Mailchimp and Sendgrid.

Its topics and documentation point to features such as sending mail, newsletters, SQLite-based storage, push notifications, and calendar and contact support through CalDAV and CardDAV, plus autodiscovery records and Domain Connect integration for setting up DNS. The README includes a local development guide and detailed notes on server infrastructure, load balancing, provisioning and deployment, including automated setup with Ansible.

The code is JavaScript and the project says it is fully open source, so the service can be inspected and, with the published infrastructure guidance, run on your own servers. Most consumers simply use the hosted service at forwardemail.net. It suits individuals and small organizations that want private email on their own domain and developers interested in how such a stack is built.

UnInbox is an open-source communication platform that reimagines email for teams and professionals. Its README argues that email has changed little since the late 1970s while volume and noise have grown, so it builds a modern layer on top of email rather than trying to replace it. The project lists Hey, Front and Missive as products it is an alternative to.

Features described as native include team collaboration, conversation notes and a new-sender screener. It is built to work with your current email infrastructure or to replace it entirely, and the maintainers say email is only the start of a broader communication infrastructure. A hosted app is live at app.uninbox.com, and the team asks users to join its Discord for updates and feedback.

The stack is TypeScript with Next.js and React for the web app, Hono for the public API, Tailwind CSS and tRPC for type-safe APIs. The repository metadata lists the license as Other, so check the license file for the exact terms. It is positioned as open communication infrastructure that teams can build on.